Gravity or turbulence? Gaia observations through Orion

Two models of molecular cloud dynamics are in the literature. On one hand, the “turbulent” one, where MCs are supported by turbulence over several free-fall times. On the other hand, the “hierarchical and chaotic global collapse” one, which states that as MCs form, they collapse, form stars and disperse, all within a few free-fall times. In this one,  the non-thermal motions that people interpret as turbulence are generated by the collapse itself, but they are hardly a mechanism that supports clouds.  Both models of MCs reproduce important observational features of MCs. Using Gaia EDR3, we have found what appears to be a distinctive feature that may allow us to disentangle which model of cloud formation and evolution is at play in MCs: the velocity dispersion of the newborn stars as a function of the mass of the stars. While turbulence models show that massive stars rapidly acquire high velocity dispersion, collapsing models show the distinctive signs of violent relaxation, where the velocity dispersion does not depend on the mass bin of the stars.

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Grain size substructures inferred from multi wavelength dust continuum emission at ALMA wavelengths

Constraining dust properties of planet-forming disks via high-angular-resolution observations is fundamental to understanding how solids are trapped in substructures and how dust growth may be favored or accelerated therein. We use ALMA dust continuum observations of the Molecules with ALMA at Planet-forming Scales (MAPS) disks and explore a large parameter space to constrain the radial distribution of solid mass and maximum grain size in each disk, including or excluding dust scattering. In general, we found that the dust surface density and maximum grain size profiles decrease from the inner disks to the outer disks, with local maxima at the bright ring locations, as expected from dust trapping models. The inferred maximum grain sizes from the inner to outer disks decrease from ~1 cm to ~1 mm. For some disks, two grain size solutions are compatible with their observed inner disk emission: one solution corresponding to a maximum grain size of a few millimeters, and the other corresponding to a size of a few hundred micrometers.

The Role of Ecology in Star and Planet Formation

Most stars and planets form in clusters/associations with hundreds of low-mass stars and their associated planetary systems forming alongside each high-mass star. Radiation, energy, and momentum from the highest mass stars permeate these regions and play a central role in shaping the demographics and habitability of exoplanets. Ionizing radiation from high-mass stars truncates and destroys protoplanetary disks around nearby low-mass stars, reducing the timescale for planet formation. At the same time, short-lived radioactive elements synthesized in the death of these same high-mass stars may regulate the water budget of Earth-like (terrestrial) planets. As the exoplanet community steps ever closer to detecting Earth-analogs, there is an urgent need to study the more distant and higher mass environments where the majority of stars/planets form and test how it impacts the demographics of exoplanets.I will discuss three key ways that the star-forming environment affects planet formation and the on-going surveys I am leading to constrain the role of environment in shaping the outcome of star and planet formation.

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The Nearby Evolved Stars Survey

Asymptotic giant branch (AGB) stars drive the chemical evolution of galaxies — the gas and dust ejected in slow winds from these objects seeds the formation of the next generation of stars. Over the past two decades, advanced space-based infrared facilities have allowed us to identify and characterise the properties of AGB stars in galaxies in the Local Group. Studies of Galactic AGB stars, however, are impeded by the foreground extinction and confusion in the Galactic Plane, which complicate the distance estimation. The recent availability of Gaia parallaxes for the nearest evolved stars has somewhat alleviated this problem. By augmenting these data with a new method of distance estimation, we identify a sample of ~850 nearby (<3 kpc) evolved-star candidates. This volume-complete sample is studied as part of the Nearby Evolved Stars Survey (NESS; https://evolvedstars.space). The NESS data consist of observations of the CO J = (2-1) and (3-2) rotational emission as well as sub-millimetre continuum using the James Clerk Maxwell Telescope (JCMT) and Atacama Pathfinder EXperiment (APEX), with data at other wavelengths from facilities such as the Nobeyama Radio Observatory (NRO).

¿Qué falta para consolidar la Igualdad de Género en la UNAM?

A través de políticas institucionales, acciones y creación de instancias, en la UNAM se ha promovido la igualdad de género como un tema prioritario dentro de la comunidad universitaria; sin embargo, todavía están pendientes muchas brechas por cerrar y mientras estas brechas estén presentes no podemos hablar de una verdadera igualdad de género. Por esta razón, el objetivo de la plática es proporcionar datos e información a la audiencia sobre las desigualdades que persisten en la UNAM. Para esto, se retomarán los conceptos "sexo" y "género", los cuales ayudarán a entender lo que es la igualdad de género, posteriormente, hablaremos de los vacíos que tiene la transversalización de la perspectiva de género en la universidad.

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Propedeuticos discussion

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Jets en envolventes comunes: el caso de una estrella de baja masa dentro de una gigante roja

La fase de envolvente común (CE) es una etapa clave durante la evolución de un sistema binario. Es unafase de corta duración, en la que la envolvente de la componente estelar más masiva engulle a laestrella menos masiva. La CE es clave en la producción de fenómenos transitorios y de alta energía talescomo supernovas, GRBs, y ondas gravitacionales, entre otros. Queda por entenderse que mecanismo omecanismos dominan durante esta fase e incluso como dicha fase termina.En esta plática daré una breve introducción sobre la fase de CE así como la posible importancia quelos jets pueden tener en dicha fase. En específico, ahondaré en el caso de una estrella de secuenciaprincipal la cual eyecta dos chorros y que se encuentra dentro de la CE de una gigante roja.

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Early Star Formation in Molecular Clouds: A comprehensive Atlas with ALMA and SOFIA

High–mass stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, they are very rare and their formation is still not well understood. High-mass, cold, dense clouds are the nurseries of high-mass stars. Mainly I will be discussing two projects that I am currently leading.  One part of my talk will focus on a large systematic search for Cold Cores with ALMA (CoCoA). With a survey machine like ALMA, CoCoA aims to reveal the truly high-mass starless cores if they exist. SIMPLIFI is a SOFIA HAWC+ Legacy pilot program that is carrying out the first high resolution large-scale study of the magnetic polarization of filaments.  Our understanding of star formation has been revolutionized by the insight that star-forming cores and hubs are embedded in complex filamentary networks that penetrate molecular clouds. Fragmentation as well as level of star formation within filaments differ greatly. Still, the exact role of filaments in star formation remains unclear. In particular, magnetic fields might play an important role, as indicated by well-ordered polarized dust emission that imply strong magnetic fields.  The aim of SIMPLIFI is to clarify the role of magnetic fields in star-forming filaments, and provide a framework to “simplify” the diversity of filament properties. filamentary networks that penetrate molecular clouds. Fragmentation as well as level of star formation within filaments differ greatly. Still, the exact role of filaments in star formation remains unclear. In particular, magnetic fields might play an important role, as indicated by well-ordered polarized dust emission that imply strong magnetic fields.  The aim of SIMPLIFI is to clarify the role of magnetic fields in star-forming filaments, and provide a framework to “simplify” the diversity of filament properties.

2012-2022 TEN YEARS WITH

In an era where observing facilities are providing enormous amounts of high precision stellar data, the reliability of our theoretical predictions is challenged by our still incomplete understanding of the complexity of some macroscopic physical phenomena (accretion, convection, rotation, mass-loss, to list a few of them). This has a significant impact on the derived physical parameters, like stellar age, initial mass, initial composition, etc... Using our stellar evolution code "PARSEC", I will focus on the following aspects that deserve particular attention. Pre-main sequence models and the Zero Age Main Sequence of low mass stars. The role of convective and rotational mixing on the evolution of intermediate mass stars. Mass-loss and the advanced evolution of very massive stars.

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Fragmentation and protostellar cluster formation

Most stars in our Galaxy are born in clusters. How molecular clouds collapse and fragment to give rise to a cluster of stars with a range of stellar masses remains an open question. The physical conditions in clouds harboring protoclusters limit the Jeans mass to about 1 Msun. This creates a puzzle for massive star formation since dense cores much greater than 1 Msun tend to further fragment into lower mass cores. Recent sensitive and high angular resolution observations of cluster forming clouds begin to unravel the complex process of fragmentation. My talk will review the recent progress in fragmentation studies. I will present observations of protocluster forming clumps and discuss the role of turbulence and magnetic fields in the formation of protostellar cores.

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Revisiting spherical gravitational collapse

I will revisit the hypotheses leading to the classical quasi-static prestellar evolution for dense cores, followed by inside-out collapse during the protostellar stage. These hypotheses appear virtually unrealizable in practice, and when more realistic initial conditions are considered, the actual prestellar evolution should be closer to the dynamic "early path" solution of Whitworth & Summers 1985, for which the infall speed decreases to zero at the core's center. Synthetic observations of simulations of this regime of collapse suggest that traditional methods of inferring the infall speed systematically underestimate it by factors of a few, sufficient to make a supersonic flow to appear subsonic. I will then describe a model for the dynamic evolution of the density profile from the onset of collapse to the formation of a protostar, showing that its logarithmic slope approaches a value of -2, and that, for slopes shallower than -2, the radial dependence of the mass accretion rate implies that the core accumulates mass, allowing it to grow. Most observed cores show slopes shallower than -2. Also, there is always an inner part of the core that is locally Jeans-stable, and grows by the compression of the outer parts. This suggests that apparently "pressure-confined" cores may actually be undergoing collapse even if they appear Jeans-stable, if they are the tip of a larger-scale collapsing cloud. Similarly, in the magnetic case, there is always aninner part that is always magnetically subcritical, but is compressed bythe outer supercritical parts. I will then describe a model for the dynamic evolution of the density profile from the onset of collapse to the formation of a protostar, showing that its logarithmic slope approaches a value of -2, and that, for slopes shallower than -2, the radial dependence of the mass accretion rate implies that the core accumulates mass, allowing it to grow. Most observed cores show slopes shallower than -2. Also, there is always an inner part of the core that is locally Jeans-stable, and grows by the compression of the outer parts. This suggests that apparently "pressure-confined" cores may actually be undergoing collapse even if they appear Jeans-stable, if they are the tip of a larger-scale collapsing cloud. Similarly, in the magnetic case, there is always an inner part that is always magnetically subcritical, but is compressed by the outer supercritical parts.

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Independent cosmological constraints from high-z H II galaxies: new results from VLT-KMOS data

I will show independent constraints of cosmological parameters using the distance estimator based on the established correlation between the Balmer line luminosity, L(H β ), and the velocity dispersion (σ ) for H II galaxies (HIIG). These results are based on new VLT-KMOS high spectral resolution observations of 41 high-z (1.3 ≤ z ≤2.6) HIIG combined with published data for 45 high-z and 107 z ≤0.15 HIIG.

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Angular Structure of Jets in Gamma-Ray Bursts

The angular structure of ultra-relativistic jets in gamma-ray bursts emerges from their interaction with the confining medium, which the jets must propagate through and break out of to produce the prompt gamma-rays. Important role in shaping up the angular structure is played by the composition (baryonic Vs magnetically dominated) of these outflows, which remains an open question. Several semi-analytical works and numerical simulations are devoted to understanding the basic “universal” structure of GRB jets, making it a very active topic of research. Complementary information comes from the afterglows produced by misaligned jets, and a golden opportunity was presented by the afterglow of GW170817 — the first multi-messenger binary neutron star merger with coincident gravitational wave and electromagnetic detections. In this talk, I will discuss how our understanding of GRB jets have evolved over the years, moving from uniform top-hat jets to jets with angular structure. Recent hydrodynamic numerical simulations are suggesting some “universal” features that are present in the angular structure of these jets. However, they do differ in important ways from their MHD counterparts. I will show how the afterglow emission derived from parameterized phenomenological structure models, as well as those obtained from numerical simulations, are used to obtain useful constraints. Here, I will particularly emphasize the afterglow modeling of GW170817. In the end, I will discuss two of my recent works on this topic that present a systematic way to understand the diversity in GRB afterglows from misaligned jets, where I will also highlight differences between steep and shallow jets.

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Exoplanet Hunting with the Radio Astrometry Technique

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A closer look at the building blocks of planetesimals: characterizing the dust content of protoplanetary disks

The dust content of protoplanetary disks plays a crucial role in the planet formation process. The key ingredients are not only the total budget of solid mass and the dust particle size distribution, but also how these are distributed throughout the protoplanetary disk. A detailed, high-resolution characterization of the dust content of disks and their substructures is therefore essential to improve our understanding of planet formation. In this talk I will describe our current observational knowledge of the dust content of protoplanetary disks. I will show recent detailed studies of various protoplanetary disks that we have performed using multi-wavelength high-resolution observations taken with ALMA and VLA. Using these data, we can estimate the dust density and dust particle size distribution of the disk substructures. Our results show that ring substructures are efficiently trapping large dust particles and can represent ideal locations to form new generations of planetesimals. Additionally, we find that the dust masses measured in all demographic studies might be severely underestimated. However, our analyses also show that disk substructures are mostly optically thick even at 3 mm. This severely limits our ability to characterize their dust content, especially in the inner tens of au where most planets are thought to be formed, including our own Solar System. I will discuss some future prospects to circumvent these issues and further improve our understanding of planet formation.

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Hunting kinematic planetary signatures through channel-map modelling

I will present recent work on the detection of gas substructure and localised velocity perturbations possibly driven by two unseen giant planets in the disc of HD 163296 as traced by 12CO. The study is performed using the Discminer channel-map modelling tool, which features a statistical technique to identify significant deviations from Keplerian rotation in both orbital radius and azimuth in the disc. The Discminer models are also well suited for studies of the gas properties and vertical structure of discs through the analysis of line profile attributes, from which we found that one of the planets in HD 163296 could also be triggering enhanced turbulent motions around its orbit. Finally, I will present preliminary results of applying the same techniques on high velocity resolution data of the discs around MWC 480 and AS 209.

The Molecular Clouds of the Andromeda Galaxy

In this colloquium I will describe the results of a deep SMA broadband (230 GHz) continuum and CO line survey of ~100 individual giant molecular clouds (GMCs) from across the nearby Andromeda galaxy (M31). The survey has produced the first simultaneous measurements of resolved emission from both dust continuum and the primary isotopologues of CO in the individual GMCs of an external galaxy. The goal of the survey is to provide knowledge of the basic physical properties of a large population of GMCs within an external galaxy in a detail as close as possible to that obtained for the GMC population in the Milky Way. To that end the M31 survey has produced the first dust calibrated mass-to-light (M/L) conversion factors for all three CO isotopologues in the individual GMCs of an external galaxy. The M/L ratio has also been measured for HCN in a subset of GMCs with coordinated NOEMA observations. In addition to resolved maps of dust continuum emission the SMA survey has provided very deep CO observations resulting in high fidelity measurements of the masses, sizes and internal velocity dispersions of M31’s GMCs, in turn, allowing high quality measurements of Larson’s Scaling Laws for the GMC population of M31. Finally, I will briefly discuss the results of a new systematic study of the gas and dust in GMCs of the local Milky Way so that I can compare in detail the physical properties of the two cloud populations. This comparison will show that the properties of GMCs in the two galaxies turn out to be quite similar. If time permits, I will discuss the implications of these results for understanding the nature of star formation scaling laws in galaxies.

Accretion effects in prestellar structures

Molecular clouds and their substructures should not be considered as isolated entities, but as part of a *continuum* distribution of fluid. In the prestellar stage, gravity and mass accretion provide two important mechanisms for interaction between these dense structures and their environment. For a simplified spherical clump model, the gravity-driven accretion compresses the innermost region of the clump, thus impeding the expansion of this sub-Jeans region without the need of external pressure confinement. This accretion leads to a clump mass growth, continuously changing the amount of mass available for gravitational collapse, until the accretion stops by stellar feedback, for example. This suggests a mechanism to relate the clumps' mass and the maximum stellar mass that can be formed in it. At molecular cloud scales, gravitational collapse increases mass distribution asymmetries, leading to flattened and then filamentary structures, with mass accretion connecting the different scales. As a gas parcel is accreted, it will experience changing density, extinction, and temperature conditions, thus changing the abundances of molecular species. The time-dependent abundance of a rapidly forming molecule will better reflect the local gas conditions than the abundance of a more slowly forming molecule. Thus, the relative abundance of molecular species should be affected by how rapidly the physical conditions change, providing a possible observational diagnostic of mass accretion.

Why molecular clouds are gravitationally dominated?

Observational and theoretical evidence suggests that a substantial population of molecular clouds (MCs) appear to be unbound, dominated by turbulent motions. However, these estimations are made typically via the classical virial parameter $\alpha _{\rm vir}^{\rm class}$, which is an observational proxy to the virial ratio between the kinetic and the gravitational energy. This parameter intrinsically assumes that MCs are isolated, spherical, and with constant density. However, MCs are embedded in their parent galaxy and thus are subject to compressive and disruptive tidal forces from their galaxy, exhibit irregular shapes, and show substantial substructure. We, therefore, compare the typical estimations of $\alpha _{\rm vir}^{\rm class}$ to a more precise definition of the virial parameter, $\alpha _{\rm vir}^{\rm full}$, which accounts not only for the self-gravity (as $\alpha _{\rm vir}^{\rm class}$), but also for the tidal stresses, and thus, it can take negative (self-gravity) and positive (tides) values. While we recover the classical result that most of the clouds appear to be unbound, having $\alpha _{\rm vir}^{\rm class}\gt 2$, we show that, with the more detailed definition considering the full gravitational energy, (i) 50 per cent of the total population is gravitationally bound, however, (ii) another 20 per cent is gravitationally dominated, but with tides tearing them apart; (iii) the source of those tides does not come from the galactic structure (bulge, halo, spiral arms), but from the molecular cloud complexes in which clouds reside, and probably (iv) from massive young stellar complexes, if they were present. (v) Finally, our results also suggest that, interstellar turbulence can have, at least partially, a gravitational origin.

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On wave interference in planet migration: dead zone torques modified by Rossby wave instability and active zone forcing

The gravitational interaction between the spiral waves generated by a planet and the spiral waves generated by a vortex in a gas disc can substantially modify planetary migration. Here, we investigate planetary migration in the dead zone of a protoplanetary disc where there are a set of spiral waves propagating outward (inward) due to: (i) The spreading of two pressure bumps and vortex formation in a gas-dust disc. (ii) The turbulence in the active zone and the Rossby wave instability (RWI) formed in the dead zone in a gaseous disc. We perform multifluid 2D hydrodynamical simulations (the dust is treated in the pressureless-fluid approximation), and global 3D unstratified magnetohydrodynamical (MHD) simulations of a gaseous disc with the FARGO3D code. We find in the first case that the vortex-induced spiral waves strongly interact with the spiral waves generated by low- to intermediate-mass planets ($M_p \in[0.06-210]\,M_{\oplus}$), it facilitates much slower and/or stagnant migration of the planets and it excites their orbital eccentricities in some cases. On the other hand, in the second case we find that once the Rossby vortex develops, spiral waves in the dead zone emerge and interact with embedded migrating planets by wave interference, which notably changes their migration. The inward migration becomes faster depending on the mass of the planet, due mostly to the constructive (destructive) interference between the outer (inner) spiral arm of the planet and the set of background spiral waves propagating inward. The constructive wave interference produces a more negative Lindblad differential torque. Lastly, for massive planets embedded in the dead zone, we find that the spiral waves can create an asymmetric wider and depeer gap than in the case of $\alpha$-discs, which could generate a faster or slower migration compared to the standard type-II migration.

The high abundance discrepancy problem in planetary nebulae through the eyes of a MUSE

The discrepancy between chemical abundances computed using optical recombination lines (ORLs) and collisionally excited lines (CELs) is a major unresolved problem that has been plagued nebular astrophysics in the last 70 years, and is generally characterized by the ratio between ORL and CEL abundances, i. e. the abundance discrepancy factor (ADF). In particular, In planetary nebulae (PNe) with large abundance discrepancies, there is increasing evidence that such discrepancy is caused by the presence of two gas phases: a hot component with standard metallicity, and a much cooler plasma with a highly enhanced content of heavy elements relative to hydrogen. Recent findings show that the largest abundance discrepancies are reached in PNe with close binary central stars and support the fact that probably two different gas phases coexist in these nebulae and that high abundance discrepancies can be explained in a framework of binary evolution. In this talk I will focus on the recent results obtained based on the analysis of IFU MUSE data of some high-ADF PNe .

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Massive Star Formation: Near and Far

Massive stars play important roles across cosmic history, and thus it is a fundamental problem to unveil if their formation processes are universal or diverse in various environments. Theoretical studies have suggested some degrees of metallicity dependence of massive star formation. Our models predicted that, in metal-poor environments of <1e-2Zsun, protostellar disks are significantly unstable, and feedback is more significant. On the other hand, observational studies of individual star formation in sub-pc scales are primarily limited to the solar-metallicity Galactic disk. Hence, we are executing a new ALMA survey targeting massive protostars in the Large and Small Magellanic Clouds (LMC and SMC; ~0.5 and 0.2 Zsun), exploring dynamics and chemistry in low-metallicity star formation. We found that the outflow properties of LMC protostars (mass, momentum, energy) are consistent with those of Galactic protostars, suggesting the universality of massive star formation at least in the range of ~0.5-1Zsun. In this talk, I will introduce our theoretical and observational studies on massive star formation in our Galaxy and beyond.

Galaxy post-processing in major cluster mergers

Galaxies undergo transformation in high-density environments such galaxy clusters, by getting their star formation quenched and transforming structurally. These galaxy clusters however grow hierarchically through large-scale cluster mergers, and are usually identified through Mpc-scale shocks in cluster X-ray and diffuse radio continuum emission. The effect of such dynamic activity on cluster galaxy properties however is poorly understood, largely due to lack of dedicated studies of galaxy evolution in merging cluster systems and contradictory evidence supporting both enhanced star formation and quenching as a result of major-merging of galaxy clusters. Our investigation with merging cluster Abell 3376 ( A3376) attempted to disentangle this by suggesting for the first time a multi-fold environment effect observed on member galaxies - from high-density environment since before the merger and a probable merger-induced sustained star formation. This talk will present the results from our ongoing study extending this to the first ever homogenous comparison of a sample of three major cluster mergers -namely A3667, A3376, and A168 - to look for merger-induced post-processing signatures in galaxy star formation history and current star formation. Employing the wide-field OmegaWINGS spectroscopic and photometric survey data and complementary multiwavelength data , I will also discuss how various aspects of cluster merging process result in the environment-dependent trends we observe in these merging clusters thereby highlighting the complex nature of galaxy post-processing due to major cluster mergers.

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Plasma analysis and central star properties of PC 22

Presentaremos el análisis de la nebulosa y estrella central de la Nebulosa Planetaria (NP) PC 22. En particular esta charla mostrará como el uso combinado de varias herramientas permiten estudiar las características de objetos de bajo/medio brillo superficial. Entonces mostraremos cómo se usaron los códigos PyNEB (y el análisis Monte Carlo para la determinación de los errores) y un algoritmo de machine learning para los ICFs respecto al estudio de plasma de la nebulosa de un lado; y la base de datos Mexican Million Models (3MdB) y código de atmósfera NLTE PoWR para el estudio de las características de la estrella central. La combinación de toda esta información nos permitió determinar las propiedades físicas de la ahora establecida NP de tipo [WR] PC 22.

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Seeking habitable regions in the nearby Universe

We only have one single example of life in the Universe, which introduces a strong bias in our perception of which could be the conditions required for its existence. Despite this bias, we can fairly assume that any habitable earth-like planet should be formed in an environment rather similar to the solar neighborhood in terms of chemical composition, distribution of stellar populations, and in general star-formation and chemical enrichment history. Under this assumption, and considering that all those properties are deeply coded in the Solar Neighborhood spectrum, we seek for Solar Neighborhood Analogs (SNAs) in the nearby Universe, constraining the probability to find habitable regions. We introduce a novel nonparametric method to find these SNAs using extragalactic integral field spectroscopic surveys. The main ansatz is that the physical properties of the solar neighborhood (SN) should be encoded in its optical stellar spectrum. We assume that our best estimate of such a spectrum is the one extracted from the analysis performed by the Code for Stellar properties Heuristic Assignment (CoSHA) from the MaStar stellar library. It follows that finding SNAs in other galaxies consist in matching, in a χ2 sense, the SN reference spectrum across the optical extent of the observed galaxies. We applied this procedure to a selection of CALIFA galaxies, by requiring a close to face-on projection, relative isolation, and non-active galactic nucleus. We explore how the local and global properties of the SNAs (stellar age, metallicity, dust extinction, mass-to-light ratio, stellar surface mass density, star-formation density, and galactocentric distance) and their corresponding host galaxies (morphological type, total stellar mass, star-formation rate, and effective radius) compared with those of the SN and the Milky Way (MW).  We find that SNAs are located preferentially in S(B)a-S(B)c galaxies, in a ring-like structure, which radii seem to scale with the galaxy size. Despite the known sources of systematics and errors, most properties present a considerable agreement with the literature on the SN. We conclude that the solar neighborhood is relatively common in our sample of SNAs. Our results warrant a systematic exploration of correlations among the physical properties of the SNAs and their host galaxies. We reckon that our method should inform current models of the galactic habitable zone in our MW and other galaxies

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Políticas universitarias para prevenir y erradicar la violencia contra las mujeres

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The role of the magnetic field in the formation of stellar clusters

Theoretical and numerical works clearly indicate that a strong magnetic field should suppress fragmentation in massive dense cores, the stellar cluster precursors. However, this has never been tested observationally in a relatively large sample of fragmenting massive dense cores. Here we present the polarization data obtained with the Submillimeter Array Legacy Survey of Zhang et al. to build a sample of 18 massive dense cores where both fragmentation and magnetic field properties were studied in a uniform way. We measured the fragmentation level within the field of view common to all regions, of ∼ 0.15 pc, with a mass sensitivity of about 0.5 Msun, and a spatial resolution of ∼ 1000 AU. On the other hand, the magnetic field strength was estimated using different methods for which the dispersion of the polarization position angles, the velocity dispersion of the H13CO+(4–3) gas, and the density of each core, all averaged within 0.15 pc, were measured. For the first time, a tentative correlation was found between the fragmentation level and the mass-to-magnetic flux ratio, as predicted by numerical and theoretical works. This suggests that the magnetic field could play a role in the fragmentation process of stellar cluster precursors, and prompts to carry out further projects using larger samples and more sensitive arrays.

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Sustainability in the IRyA and the UNAM

The Sustainability from the UNAM Plan (PISU), published in 2022, aims to include sustainability in all of the main activities of the University - teaching, culture and research - and also encourages the participation of the university community in initiatives that promote sustainability at local, national and global levels. Since 2019 the IRyA has had a Local Sustainability Commission and in this talk I will describe the activities that we have carried out within the institute and the links that we have with other entities of th Morelia Campus and with the UNAM on issues related to sustainability. I will talk about the initiatives that exist at a local and global level that can contribute to making our activities within and outside the IRyA more sustainable.

The ups and downs of galaxies

In the past years, ground-based and space telescopes have given us inestimable information about the Universe we leave in. We can now study the physical properties of galaxies from the present day, up to 13 billion years ago. Such quantity and quality of data require more and more advanced tools to make the most of the observations. We have thus built a physically motivated library of galaxy spectral energy distributions by combining predictions from cosmological simulation with state-of-the-art models of the stellar and nebular emission and the effect of dust. Our approach allows us to constrain the star formation histories of galaxies and assess how galaxies form, evolve and, after some ups and downs, eventually quench their star formation and evolve passively. I will present the constraints we derive from observations of local and high-redshift galaxies on their evolutionary timescales as a function of stellar mass, and I will also present some work on dust laws in galaxies at redshift one.

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Opening new windows for messages from cosmic influencers: massive stars in the era of gravitational wave astronomy

Stars with masses much higher than our Sun end their short lives in a gravitational collapse, leaving behind neutron stars and black holes. The detections of gravitational waves (GW) brought massive star astrophysics into the new multi-messenger era. A comprehensive understanding of massive star lives and deaths is urgently required to fully unleash the power of multi-messenger astronomy. In this talk I will briefly review our empiric knowledge about massive stars, and highlight the key problems in our current understanding of neutron star and black hole progenitors. I will further discuss the potential of high-mass X-ray binaries to constrain the evolutionary channels leading to GW events. Finally, I will discuss what we are learning about massive star and X-ray binary feedback in different cosmic environments and times.

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Multiphase gas, star formation and AGN activity in jellyfish galaxies

I will present results from the GASP (GAs Stripping Phenomena in galaxies) survey whose aim is to study the physical processes that remove gas from galaxies in different environments. I will focus on galaxies in clusters and, in particular, on the ongoing star formation activity and its relation with gas in different phases (ionized, neutral, molecular), both in the galaxy disks and in the tails of stripped gas that are observed at different wavelengths. The most spectacular such cases are known as "jellyfish galaxies". I will show the latest results regarding the star-forming clumps in these tails and I will discuss the star formation history and the quenching induced by ram pressure stripping. Finally, I will show the existing evidence for a possible causal relation between the stripping and the AGN activity.

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La política institucional de la UNAM para atender la violencia de género

La plática tiene como objetivo dar a conocer el proceso que vivió la Universidad en la adopción y fortalecimiento de su política de género durante los últimos cuatro años. Especialmente se abordarán los principales retos, avances y nuevos desafíos de la política en materia de atención y prevención de la violencia de género dentro de la UNAM.

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Revisiting Attenuation Curves - Then and Now

Over the next  decade, several facilities will come on-line which will observe the restframe UV/optical emission of galaxies  across the entire span of cosmic time, yielding samples of millions of  spectral energy  distributions (SEDs). Measurements of star formation rates (SFRs), masses, and other physical parameters  from those SEDs will enable comparisons with models of galaxy evolution with unprecedented accuracy. However, the derivation of physical parameters from observed SEDs requires removing the effects of  dust  attenuation. (Sub)mm facilities will not be able to provide sufficient areal coverage and sensitivity  to observe those  millions of galaxies. This implies that IR-based dust corrections will  be  difficult to extend to large galaxy samples. For most galaxies, dust  attenuation removal from their UV-optical SEDs will require the use of attenuation curves. I will review the current state  of our understanding of attenuation curves at  low and high redshift, highlight both their strengths and weaknesses, and discuss what  steps may be able to move the field forward.

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One year of outreach during the pandemic: the good, the bad and the ugly

A year after the first "work from home" order, I will talk about some of the advantages and difficulties of doing viritual-only outreach and science communication at IRyA during the Covid-19 pandemic. I will comment on outreach projects for the rest of 2021 and I will make a case for the continued use of mixed and virtual-only formats along traditional in-situ events for outreach and science communication once in-person activities resume.

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A Radio Pinwheel Associated with WR147

Wolf-Rayet (WR) stars are evolved massive stars, characterized by high luminosities and fast and dense stellar winds. We have detected a radio continuum pinwheel associated with WR 147, a nitrogen-rich WR star. These structures have been detected in the infrared around a handful of late-type carbon-rich WR stars with massive companions, where dust has formed in the zone where the two winds collide and produced a plume of dense gas and dust that is carried out with the WR wind. As the binary system rotates, an Archimedean spiral is produced. The resulting pinwheel contains information on wind speeds, wind-momentum ratio, and orbital parameters. However, WR 147 is a WN star and the formation of dust is unlikely, so a different emission mechanism must be at work. Our analysis of the data suggests that in this case the emission is dominantly of a nonthermal nature (synchrotron). It is possible that the pinwheels associated with WN stars will be detectable only as nonthermal emitters at radio wavelengths. From the characteristics of the pinwheel we estimate a period of 1.7 yr for the binary system (the WN star and a companion yet undetected directly) that is responsible for the pinwheel.

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Observations of Atomic Hydrogen at Cosmic Dawn

After the epoch of recombination at z = 1100 the Universe entered into the so-called Dark Ages, when hydrogen was neutral and observations have not been possible until recently. Gamma-ray bursts have been detected at values as high as z = 11. But between these two values of z there were no detections. In 2018 the EDGES collaboration reported the detection of highly redshifted HI in absorption between z = 15 and 20. The depth of the absorption cannot be explained in terms of standard cosmology and three possible explanations have been proposed: 1) the observations are wrong, 2) there is an exotic physics process and 3) there is an additional radio background to the known cosmic background. I will discuss possible radio sources that could account for the last possibility.

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First Observations of the New MEXART's Digital System

The Mexican Array Radio Telescope (MEXART) is a transit instrument mainly dedicated to perform Interplanetary Scintillation (IPS) observations of extragalactic sources with a central operation frequency of 139.6 MHz. The main scientific objective is to perform studies of solar wind properties and space weather perturbations. The site is located in Coeneo, Michoacan (19.810 N, -101.690 W) at about 80 km from Morelia. The antenna contains 4096 fullwavelength dipoles ordered in a 64x64 array. In 2016, the observatory became the main site of the National Space Weather Laboratory (LANCE). The MEXART was originally operating with a 16x16 Butler Matrix, which produced 16 fixed latitudinal beams at different declinations. Using 1/4 of the antenna (16 E-W lines), the MEXART began operations and reported the first measurements of IPS sources, the detection of solar wind transient events, and the systematic observations of a few IPS sources to infer the yearly variation of their scintillation index. However, the MEXART’s analogue back-end system had several problems. The 16 beams produced by the Butler matrix had poor directivity (with very large secondary beams), which caused significant gain losses and that the instrument did not reach the expected performance. Problems with the antenna signals arriving at the backend, in power and phase, did prevent that the radio-telescope could detect the number of radio sources required to monitor the solar wind between the Sun and the Earth. In order to solve this problem, we commissioned the design and construction of a new backend’s digital system. The new digital system solved the problems with the beam forming system, increased the bandwidth and improved the instrument’s sensitivity. We present the first light of the MEXART’s digital system. We describe the new technical capabilities of the instrument, and we show some preliminary results: an estimation of the instrument’s sensibility, the observation of the transit of the Galaxy at 140 MHz, and some IPS observations.

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Dynamical star formation from Milky Way cloud scales to hundreds of AU

Star formation processes are important over a huge range of physical scales, from large atomic and molecular clouds down to the scales of individual protostellar cores disks around stars. Linking these scales is crucial for a general understanding of star formation and the interstellar medium. I will set into context results from Milky Way cloud scales to individual star-forming regions and dense cores with an emphasis on the dynamical properties of the star formation processes.

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Mapping the Universe with 4m Telescopes

The availability of wide-field telescopes equipped with CCD imaging cameras and, more recently, very wide field spectroscopic capabilities, is revolutionizing discovery in astronomy. I will describe the Legacy Surveys project which has created one of the largest, public, deep optical catalogs of the sky. The Legacy Surveys is being used for selecting targets for a cosmology survey with the Dark Energy Spectrospic Instrument (DESI). I will present an overview of the goals, construction, and current status of the DESI project, which aims to create the largest cosmographic map of the universe and investigate its expansion history with unprecedented precision, as well as map the kinematics of many millions of stars in our Galaxy.

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Can supernovae be important source of dust in the interstellar medium of galaxies?

In the last decade, Spitzer, Herschel and ALMA have opened up a new era of supernova studies. New findings include detections of dust and molecules from supernovae and supernova remnants. These findings are paving the ways to understand if supernovae can be the major source of dust in galaxies, and to constrain explosive nucleo-synthesis, that is considered to be the main source of elements in galaxies, and explosion mechanisms, which would provide kinetic energy into the interstellar medium of galaxies. I am going to present our latest observations from Herschel, ALMA and SOFIA  of supernova 1987A and Galactic supernova remnants.

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Gravotermodinámica

La gravedad es la fuerza que moldea el Universo y las galaxias, cúmulos estelares, estrellas y planetas que contiene.  De las fuerzas conocidas, es la única que afecta toda la materia y energía.  A pesar de lo sencillo de su forma funcional, su efecto puede ser muy complejo ycontra-intuitivo, pues es de largo alcance y no lineal.Al estudiar sistemas dominados por la gravedad, resulta a veces útil el estudiarlos como sistemas termodinámicos y aplicar conceptos y técnicas de esta disciplina que revelanalgunos de sus comportamientos sorprendentes.Esta no será una charla regular de presentación de resultados originales.  Mi objetivo es dar una visión amplia de un área de investigación interesante, que espero Uds. encuentren interesante también.  Hablaremos únicamente de gravedad en un regimen no-relativista.

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Interferometric imaging of Young Stellar Objects

Currently, it is well-known that low-mass stars are formed via accreting disks. During the last decade an impressive plethora of morphologies have been observed with interferometric observations at radio wavelengths (e.g., ALMA) and, more recently, with infrared coronagraphs (e.g., SPHERE/VLT or GPI). Infrared interferometers have also observed these objects, allowing us to observe the inner rims of the accreting disks and, even, to trace the emitting region of lines like BrG or CO. In this talk, we will review some examples of these discoveries made with the interferometer GRAVITY.

In search of extragalactic Wolf-Rayet stars: the case of the Antennae

Wolf-Rayet (WR) stars are considered descendants of O-type stars. They can be used as indicators of young stellar populations and to study the chemical enrichment of their environments due to their characteristic strong stellar winds enhanced with processed elements. They are also considered as the most suitable candidates for core collapse supernovae (SN) and long-duration soft-gamma ray burst. In this talk I will present the analysis of archival Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of the interacting galaxies NGC 4038/39 (a.k.a. the Antennae) at a distance of 18.1 Mpc, the nearest and youngest pair of colliding galaxies at an early stage of a merger. We report the number, classification and distribution of the WR population in star-forming complexes of the Antennae. We compare our results with stellar population synthesis models. With this work we are increasing the sample of extragalactic WR stars, SNIbc candidates and other interesting post-SN by-products.

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Photoionized Herbig-Haro objects in the Orion Nebula. Laboratories to better understand ionized nebulae.

We present some results on a project based on high-resolution UVES@VLT spectroscopy and HST imaging of photoionized Herbig-Haro (HH) objects in the Orion Nebula. We study physical conditions, chemical abundances and other properties such as proper motions and the origin of the driving jets. Our study will include at least 9 HH objets, of which we will focus on HH529II, HH529III and HH204 in this talk. Our data allow us to separate the spectrum of the outflows from the main nebular emission, studying each object with an unprecedented detail. The HHs are located at different distances from the main ionization source of the Orion Nebula, with different ionization/physical conditions and flow velocities. In all objects, the electronic density (ne) is substantially higher than in the surrounding Orion Nebula, while the electronic temperature (Te) is maintained under photoionization equilibrium for the most abundant ion stages. In HH204 we observe a Te([OIII]) gradient due to the contribution of [OIII] emission from the cooling layer behind the bow shock, which is also detected in the HST imaging. The ionization degree of the gas in the different HH objects is very different, allowing us to determine the chemical composition of the Orion Nebula under both ionization conditions, avoiding the use of ionization correction factors (ICFs) for many elements. HH204 shows an abundance discrepancy  -the difference between abundances derived from recombination and collisionally excited lines- that is actually zero. We find direct evidence of dust destruction in the bow shock in all objects. This increases the gaseous abundances of Fe, Ni and Cr with respect to the Orion Nebula ones. We show that a failure to resolve the different kinematic components -as in a low spectral resolution spectrum- can lead to significant error in the determination of chemical abundances -40% underestimate of O in the case of HH204-, mainly due to incorrect estimation of the electron density.

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PhD Talks

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The crucial role of accretion in Global Hierarchical Collapse Flow

Recent observational and numerical evidence suggests that accretionin the process of star formation occurs not only in the final step, from core to star, but rather at all scales involved. Furthermore, the accretion at each level has a number of unexpected and crucial consequences, which I will discuss in this talk. At the scale of the parent cloud, accretion from its surrounding (possibly atomic) medium counteracts the mass consumption by star formation, maintaining the instantaneously-meauserd star formation efficiency low. Moreover, it causes an increase in the cloud's mass, density, and radius, causing an evolution from a low- to a high-mass star-forming stage. At the filament level, it allows the establishment of a possibly near-stationary regime in which the filaments act as "rivers", funneling material from the cloud to the core scale. At the core scale, the accretion compresses the innermost regions, driving them to collapse even if they are not Jeans unstable. Finally, the gravity-driven mass transfer rate across the core depends on the core's radial density profile. If the density profile is shallower than r^-2, the cores are capable of accumulating mass without transferring it entirely to their central parts, and thus grow in mass and density. Therefore, accretion is one of the main drivers of evolution in star-forming structures.

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Could quantum mechanics explain the dark universe?

We know that Quantum Mechanics was developed to explain the micro-world: atoms, molecules, etc. In this talk we show how the Schrödinger equation and the simplest concepts of quantum mechanics can explain the most controversial phenomena of dark halos, such as the core-cusp problem, the number of galaxies satellites around the big ones, the anomalous behavior of the trajectories of the galaxies satellites, etc. and how elementary concepts of quantum mechanics give us an explanation for the accelerated expansion of the universe, without dark energy.

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The Cygnus Cocoon: a powerful star forming particle accelerator

In resonance to ideas put forward by Enrico Fermi more than sixty years ago, Galactic cosmic rays are generally believed to originate in supernova remnants, where rapidly moving shocks should allow for particle acceleration up to the PeV range. The development of high-energy observatories capable of scanning the Galactic Plane has enabled to test the Fermi paradigm. While supernova remnants have been found among the sources of TeV gamma rays, tracers of very high energy cosmic rays, their gamma-ray spectra do not appear to extend beyond some tens of TeV. Recent observations of the Cygnus region with the HAWC gamma-ray observatory of photons with energies in the 100 TeV range show that star forming regions are able to provide very high energy cosmic rays and may be more suitable sources at the higher energies.

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How do stars get their mass? Understanding the origin of the IMF from the mass distribution of cores

The origin of stellar masses is one of the most central open issues in astrophysics. In a pilot survey toward W43-MM1, we showed that in the extreme environments of our Galaxy the mass distribution of cores (CMFs) present an excess of high-mass objects compared to the canonical IMF. In this talk, I will introduce the ALMA-IMF Large Program, whose goal is to determine if and how the origin of the Initial Mass Function (IMF) depends on the cloud characteristics. Its first results, obtained from a large sample of cores without significant bias, suggest that CMFs of high-mass proto-clusters generally do not follow the canonical IMF. I will also present our recent detailed studies of the W43-MM2&MM3 region. We propose that top-heavy CMFs are associated with spatially and temporally limited bursts of star formation. In addition, the identification of outflows in CO(2-1) enables us to assess that a very large fraction of the excess high-mass cores are protostellar. This confirms that the high-mass prestellar core phase, if it exists, is evanescent.

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Los 'dedos de Orion' como objetos autogravitantes de baja masa eyectados en una explosion de supernova

El sistema de los "dedos de Orion" (eyectados por la fuente infrarroja BN/KL) tiene una elongacion NO-SE, y una asimetria red/blueshift respecto de un eje alineado con la direccion de maxima elongacion del sistema. Esto desafia una interpretacion en terminos de un "flujo bipolar" parcialmmente colimado. Proponemos que este sistema proviene de un disco de objetos de baja masa orbitando en torno de una estrella masiva. Al tener esta estrella una explosion de supernova, los objetos del disco pasan de tener orbitas ligadas a basicamente seguir trayectorias rectas, todas sober el plano del disco. Esta configuracion reproduce en forma llamativa la elongacion y separacion rojo/azul "lado a lado" del sistema de los dedos de Orion.

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Stellar Structures in Galaxies: Insights from the Local Universe

Galaxies in the local universe are a fossil record of events in the distant universe and present critical constraints for examining models of formation and evolution of galaxies. Based on the Spitzer Survey of Stellar Structure in Galaxies (S4G) database, we study the stellar light that is typically associated with different stellar structures (such as bulge, disk, bar, spiral arms) in an effort to construct a local reference for stellar structure studies. S4G is one of the major legacy surveys of the post-cryogenic campaign of Spitzer and is the largest, deepest and most homogenous mid-IR survey of the nearby Universe to date. Combined with deep optical follow-up, an unprecedented opportunity opens up to complement a stellar mass census with a detailed analysis of the stellar populations in stellar structures. With this in mind we have initiated an observational campaign using the Goodman imager on SOAR to go after S4G galaxies in the southern sky: the Census of Austral Nearby GAlaxies (CANGA). The CANGA survey, covering all griz bands, complements the exquisite work that has been performed by the Sloan Digital Sky Server in the northern hemisphere, but largely surpasses its sensitivity. I will show a number of discoveries we have made within the S4G data set, with a particular focus on the characterization of stellar bars, and give you a preview of the exciting work we are doing with CANGA.

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Shaping born-again planetary nebulae

Born-again planetary nebulae (PNe) represent very special cases of the evolution of low-mass stars. It is believed that they experienced a very late thermal pulse ejecting highly processed material that is H-deficient but C-rich, rendering their central stars a [Wolf-Rayet]-type. Abundance analysis of the optically-emitting nebulae seem to suggest that these objects were produced by a binary system in a nova-like evolutionary channel. In this talk I will present the analysis of dust emission from the born-again PNe A30 and A78 to demonstrate that once we take into account the C trapped into grains the abundances are consistent with the single stellar evolution scenario. In contrast, I will also present recent ALMA data on one of the youngest objects of this class, A58, which suggest that the shaping mechanisms of the H-deficient nebula is due to the presence of a binary companion.

Observational signatures of the vertical shear instability in planet-forming disk CO kinematics

The turbulent gas motions in planet-forming disks are crucial for their evolution and are thought to affect the planet formation process significantly. Recent (sub-)millimeter observations show evidence of weak turbulence in the disk’s outer regions. However, the detailed physical mechanism of turbulence in these outer regions remains uncertain. The vertical shear instability (VSI) is a promising candidate mechanism to produce turbulence in the outer parts of the disk. By performing global 3D hydrodynamical simulations of a VSI-unstable disk, and post-processing them producing synthetic ALMA observations, we studied the non-Keplerian kinematic signatures of the VSI that could be observable with the ALMA interferometer. Characterizing these signatures in high-resolution observations can confirm that the VSI operates in the outer regions of protoplanetary disks. During my talk, I will summarize the efforts studying the kinematic signatures of protoplanetary disks produced by the vertical shear instability, and present our predictions for upcoming ALMA observations of CO isotopologues.

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The Cloud Factory: resolving star formation in its galactic context

I present suites of simulations that resolve individual molecular clouds down to ~0.1 pc scales while they are embedded within a larger galaxy simulation. This enables us to study fragmentation and star formation within the resolved clouds in their true galactic context and is a perfect point of comparison to ISM observations in the ALMA era. Our Arepo simulations include a time-dependent chemical model, gas self-gravity, the ISRF and gas self-shielding, magnetic fields, sink particles, and supernova feedback. Using a Milky Way analogue and dwarf galaxy simulations of various metallicities as our base, we turn on these effects step-by-step in a series of simulations to create a laboratory for testing the physics of the ISM and star formation from kpc scales to cold cores.

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The Central Problem of Star Formation: Why So Slow?

The Central Problem of star formation has been clear for over 40 years: simple estimations predict star formation rates more than 100 times what is observed in the Milky Way and other galaxies. Much ingenious theoretical work has been expended to solve this problem, enhancing our understanding of turbulence and feedback in molecular clouds, but the fundamental problem remains. This situation suggests a reconsideration of the basic assumption that underlies the problem: that molecular clouds are bound entities. In the most complete catalog of structures from CO emission maps, most molecular clouds are unbound, ameliorating the problem. Preliminary work combining this information with theoretical models of how the star formation rate depends on the initial virial parameter, along with considerations of how metallicity affects the conversion of CO luminosity into mass, suggests that a solution to the Central Problem may be at hand for the Milky Way. The situation for other galaxies is less clear.

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Stellar orbital dynamics in steady galactic potentials

We investigate the role of 2D and 3D sticky-chaotic orbits in building boxy bar structures. The models studied originate from snapshots of N-Body simulations. We quantify the degree of chaoticity of the orbits by using the GALI2 index. The candidate orbits that construct these morphologies are located in the outer parts of stability islands. In the case of spiral arms, we use the PERLAS potential that considers massive structures. The spirals are imposed from the ILR to 1.2 times the corotation radius and the parameters of the model emulate Sc galaxies. We compute the 3D periodic orbits of the models in cases when the amplitude of the perturbation varies. These orbits are considered as the skeleton of the spiral arms. The periodic and quasi-periodic orbits support the spirals from the ILR up to the 4:1 resonance. Finally, I present some results of my last work with the GravPot16 model. In this case, we carry out spectral analysis to a set of test particles in this Galactic model. This analysis allows catching the orbits that build the galactic bar. The computed orbits generate a "peanut" structure on the edge-on view. We present the contribution of each orbital family to "peanut" morphology.

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El papel de la academia ante la violencia de género. Estrategias de atención y prevención

La conferencia abordará el papel de la comunidad universitaria en lo general, y de la academia en lo particular en el cuestionamiento, modificación y desmontaje de la ceguera de género y la violencia en la universidad. Se desarrollarán elementos que permitan visibilizar la realidad de la UNAM en materia de violencia de género y de violencia contra las mujeres, para que, desde ese lugar se sostenga la necesidad de establecer y consolidar alianzas que construyan una ética comunitaria universitaria que trascienda la confrontación entre sexos, y que deconstruya y redefina normas de género basadas en la dominación. Finalmente se presentarán algunas de las bases para elaborar un plan universitario de acción que promueva la igualdad de género y prevenga la violencia.

The molecular gas content of jellyfish galaxies

Jellyfish galaxies represent on one side a key tool to understand the galaxy evolution in galaxy clusters, but also they can lead to the understanding of the star formation process in peculiar environments (disturbed disks and stripped gas tails). I will discuss both aspects, focusing in particular on the molecular gas content of GASP jellyfish galaxies, as derived using single dish and interferometric observations at different scales.

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How fast do galaxies die? Probing quenching timescales in the green valley

Galaxies show a clear dichotomy in their properties, with blue spirals being markedly different from red ellipticals. This means galaxies must undergo some physical transformation that prevent them from further forming new stars. In this talk I will discuss a series of results from our group that aim to measure and understand star formation quenching, in particular measuring how fast this must occur. More recently, we have investigated the possible correlation between quenching timescales and other processes, in an attempt to further understand the main drivers of galaxy evolution and transformation between the two populations.

Rapidly Evolving Episodic Outflow in the Fastest Water Fountain

Water fountains (WF) are evolved stars showing early stages of collimated mass-loss during transition from the asymptotic giant branch, providing valuable insight into the formation of asymmetric planetary nebulae. We present the results of our Very Long Baseline Interferometry (VLBI) water maser observations, which determine the spatial and three-dimensional kinematic structure of the masers associated with the fastest WF IRAS 18113−2503. The water masers trace three pairs of high-velocity (~150-300 km/s) bipolar bow shocks on a scale of ~0.18 arcsec (~2000 au). The expansion velocities of the bow shocks exhibit an exponential decrease as a function of distance from the central star, which can be explained by an episodic, jet-driven outflow decelerating due to drag forces in a circumstellar envelope. We estimate an initial ejection velocity of ~840 km/s, and a period for the ejections of 10-20 yr, with the youngest being ~12 yr old. We hypothesize that IRAS 18113−2503 hosts a binary central star with a separation of ~10 au. We also explain the water maser monitoring program we are currently doing on this WF for testing some of our observational predictions.

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January IRyA Meeting

The future of planetary nebulae in upcoming X-ray missions

Planetary nebulae (PNe) are hot and emit X-rays. Chandra and XMM-Newton have unveiled in unprecedented detail the distribution of the X-ray-emitting plasmas from their inner cavities, but the relatively low spectral resolution of the observations is not able to resolve spectral lines to study abundances and physical properties. Thus, the X-ray-emitting gas in PNe can only be characterised in temperature and luminosity. In this talk I present an updated view of X-ray observations of PNe. The physical mechanisms producing X-ray emission are also discussed. Finally, we present the prospects for the upcoming X-ray missions.

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The optical morphologies of galaxies in the IllustrisTNG cosmological simulation

The latest hydrodynamic cosmological simulations (e.g., EAGLE, Illustris, IllustrisTNG) have been able to produce reasonably realistic populations of galaxies by tracking the evolution of dark matter, gas, stars, and black holes over a cosmological volume "representative" of the large-scale density field. However, making robust, meaningful comparisons to observations requires equally sophisticated analysis techniques, such as `forward modeling' of simulation data onto observer space. In recent work (Rodriguez-Gomez et al. 2019), we generated synthetic images of ~27,000 galaxies from the IllustrisTNG and the original Illustris hydrodynamic cosmological simulations, designed to match Pan-STARRS observations of log10(M*/Msun) = 9.8-11.3 galaxies in the local Universe (z = 0.05). Most of the synthetic images were created with the SKIRT radiative transfer code, including the effects of dust attenuation and scattering. In order to make an `apples-to-apples' comparison between these mock images and the real ones, a novel morphology code was developed and applied to both sets of images. In this talk, I will present some results from this comparison and briefly describe the newly developed STATMORPH code, which is publicly available (https://statmorph.readthedocs.io).

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Introducción a los servicios de cómputo del IRyA

Choked accretion: a hydrodynamical jet-launching mechanism

Astrophysical jets are ubiquitously found in the Universe, from young stellar objects to active galactic nuclei, and accompany high-energy phenomena such as gamma ray bursts, micro-quasars and compact object mergers. There are, however, several important open issues about them that we still do not fully understand, e.g. the process of launching the jet in the first place, as well as the connection between the accreted and ejected flows. In this talk, I will present a novel ejection mechanism in which, by breaking spherical symmetry, a radially accreting flow transitions into an inflow-outflow configuration that can contribute to the inner engine behind a jet-launching system. This mechanism unveils a flux-limited accretion regime in which, for a sufficiently large accretion rate, the incoming material chokes at a gravitational bottleneck and the excess flux is redirected by a density gradient as a bipolar outflow. I describe the choked accretion mechanism first in terms of an exact relativistic model based on a stiff fluid equation of state. Then I present the results of numerical simulations where the stiff fluid approximation is relaxed and show that this mechanism can operate under more general conditions. Finally, I discuss the applicability of this model as a jet-launching mechanism in different astrophysical settings.

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Numerical models of the fingers in the Orion BN / KL re

The Orion BN/KL region, which has a great diversity of molecules, has a breaking-up multiple stellar system, an expanding molecular bubble and a peculiar outflow with about 200 filamentary structures, known as ``fingers'' or ``streams''. These three components seem to have originated in the same ejected event approximately 500~yr ago. It is an example of a poorly understood phenomena in star forming regions involving the close encounter of young stellar objects. The explosive structure, the great variety of molecules observed, the energy involved in the event and the mass of the region suggest a contribution in the chemical diversity of the local interstellar medium. Here we present numerical models that can help us to clarify the mechanism that formed this event and other explosive events that have been observed.

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Unraveling the structure of a young planetary system: the case of Sz 91 transitional disk

In this talk, I will show one of the most intriguing radial disk structures identified in recent years: the ring around Sz 91--a transitional disk around an M1 star located in the Lupus III star-forming region. It poses the largest inner cavity observed in a disk around a T Tauri star: ALMA observations have revealed a narrow (<25 au), ring-like structure peaking at 95 au from the star. Fascinatingly, in contrast to the continuum, 12CO emission is detected down to <16 au and up to almost 400 au. I will present polarized light observations acquired with VLT/NaCo at H and Ks bands. We resolve the disk and detect polarized emission up to ~80 au along with a central cavity at both bands. We found that the emission is best explained by small, porous grains distributed in a disk peaking inside the submm cavity. The disk is asymmetric in polarized light along the minor axis, with the north side brighter than the south side. We also found differences in position angle between the disk observed with ALMA and our NaCo observations. This suggests that the disk that we are detecting with NaCo may be slightly warped and, therefore, could be highly structured. Dynamical clearing by multiple low-mass planets arises as the most probable mechanism for the origin of Sz 91's peculiar structure. To test this hypothesis of ongoing planetesimal formation in the ring-like particle trap around Sz 91, we aim at characterizing the distribution of particle sizes in the ring. We are currently analyzing brand new high-resolution (14 au) ALMA observations at 2.1 mm, that along with archival 1.2 and 0.87 mm data, will allow us to measure the spectral index and to constrain the radial size of the ring.

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aztekas: a general relativistic hydrodynamics code

The study of gas dynamics represents an important part of the overall understanding of the evolution of astrophysical phenomena. The highly non-linear form of the hydrodynamic equations prevents them from being solved analytically except in highly idealized cases. Therefore, for more complicated and specific scenarios, it is necessary to solve them using numerical methods. In this talk, I will briefly discuss the importance and applications of the study of fluid dynamics in astrophysical systems, as well as some of the fundamental concepts and numerical algorithms needed to solve the equations. I will present numerical tests and applications of the aztekas code in both (general) relativistic and non-relativistic regimes. Finally, the main purpose of this presentation is to invite the community of IRyA to collaborate and contribute to the development and use of the code.

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Cosmic dust laboratory: light scattering data available

Light scattering by dust particles occurs in many astrophysical scenarios at different scales: from the Earth atmosphere to interstellar medium. Modeling by spheres or other simple shapes is limited and introduces huge errors in radiative transfer models. The only feasible approach to the problem of obtaining light scattering properties of realistic particles is experiments. The cosmic dust laboratory (IAA CSIC - Granada - Spain) is an experimental setup in which scattering matrices of clouds of micron-sized particles and individual mm-sized grains are measured for wavelenghts in the visible range. These data are exportable to other regions of the spectrum as long as the ratio size/wavelength is preserved. In this colloquium I will present some recent results on light scattering experiment related to dust in the coma of comet 67P (visited by Rosetta). The freely available database of the Cosmic Dust Laboratory will be presented as well. Furthermore explanations and indications will be given about how to approach the light scattering problem in different fields on interest in Astrophysics (disks, nebulae, molecular clouds, etc.) through the light scattering database and other resources.

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Tracing Historic Mass Loss from Evolved Stars with Thermal Emission from Cold Dust

T.B.D.

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The Nearby Evolved Stars Survey: The dust and gas return to the Galactic interstellar medium

Evolved Stars play key roles, enriching galaxies with dust, gas that fuels star formation and the products of nucleosynthesis through their mass loss. For low- and intermediate-mass stars, a large part of this mass loss occurs on the Asymptotic Giant Branch through a dusty wind, while the more massive Red Supergiants undergo similar processes. I will review some recent progress in understanding the mechanisms driving this mass loss and how it enriches the ISM. I will then present some initial results from the ongoing JCMT large program the Nearby Evolved Stars Survey, which is observing a statistical sample of evolved stars in the Solar Neighbourhood. NESS aims to determine the total mass return to the Solar Neighbourhood and obtain a statistical picture of the physics of mass loss. Finally, I will explore some important avenues for future work in this field.

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Modelos Matemáticos del SARS-CoV2

En esta charla se expondrán los esfuerzos que se están realizando dentro de la UNAM para estudiar la propagación del coronavirus surgido en el 2019 en Wuhan, China.

Cosmic gas flows and how they build up galaxies

Galaxies are intimately connected to the environments they live in. The haloes around them contain the gas reservoir from which the galaxies grow, while galactic outflows heat and enrich this so-called circumgalactic medium (CGM). In this talk, I will use cosmological, magnetohydrodynamical simulations to show how the gas dynamics affects the growth of galaxies. We use a new simulation refinement technique to reach orders of magnitude higher resolution than the current state-of-the-art in order to understand the physical and observable properties of the gas around galaxies. I will show how the presence of magnetic fields alters the gas flows into and out of galaxies, giving rise to more mixing and higher gas fractions inside the halo. Our spatially refined simulations also show that the CGM has higher overdensities than previously thought, which strongly affects predicted observables in the CGM. The neutral hydrogen (HI) column density and H-alpha emission from ionised gas are dramatically enhanced, more in line with observations. 

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The origin of dust in galaxies

The evolution of interstellar dust reservoirs, and the evolution of galaxies themselves go hand-in-hand, as the presence of dust alters evolutionary drivers, such as the interstellar radiation field and the star formation history, while at the same time, the dust is being formed and altered by processes taking place in galaxies. However, far-infrared and submillimeter studies have revealed enormous dust masses at high redshifts that are difficult to explain with dust production from evolved stars (the so-called "dust budget problem"), while in the nearby universe there is also a significant mismatch between the dust production rate and the dust mass observed in the interstellar medium of galaxies. I will go over some possible explanations in an attempt to find a way forward towards a solution to this seeming discrepancy.

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The dark hearts of galaxies: molecules as dynamical probes of galaxy evolution

In this talk I will describe how mapping the dynamics of molecular clouds in the centre of galaxies can help us to constrain a wide range of astrophysical problems. From the enigmatic relation between galaxies and their supermassive black holes, the suppression of star-formation in dying galaxies, and the puzzling variation of the stellar initial mass function, molecules provide an ideal probe that can help us make progress. I will show how parsec resolution observations can be used to estimate the masses of supermassive black holes in galaxies across the Hubble sequence, and describe the WISDOM project, that aims to use this technique to constrain the importance of accreting SMBHs in galaxy quenching. I will show that the deep potential wells of massive galaxies change the small-scale structure of the ISM, suppressing star formation, and helping to keep these objects quenched. Finally I will show how one can use molecules to probe the controversial topic of variation in the stellar initial mass function.

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Stellar feedback and galaxy evolution in the era of integral field spectroscopy

Feedback from massive stars plays a central role in shaping the evolution of entire galaxies. Despite a solid qualitative understanding of feedback, our quantitative knowledge remains poor. Currently, only a small number of HII regions have adequate observational information on both gas and stars needed for detailed feedback studies. However, the growing availability of integral field unit (IFU) instruments and the novel analysis techniques we’ve developed for them, now allow the study of stellar feedback in orders-of-magnitude more HII regions than previously possible, i.e. the numbers needed to fully quantify the effects of feedback over a large dynamic range of stellar and interstellar medium properties, and to connect the results to state-of-the-art star formation and galaxy evolution models. I will discuss the first results of resolved stellar feedback studies from a MUSE IFU legacy dataset covering the nearby Sculptor galaxy NGC 300, as well as results from MUSE observations of HII regions in the Magellanic Clouds and the Milky Way. By merging the MUSE NGC 300 data with HST resolved stellar photometry, I demonstrate that ground-based IFU data of nearby galaxies is ideally suited to quantify feedback from massive stars over entire galaxies all the way down to individual cloud scales. Moreover, I will discuss the MUSE observations in terms of a pathfinder to ongoing and next-generation IFU nearby galaxy surveys, instruments, and facilities such as the Local Volume Mapper, JWST, and 30m-class telescopes. Finally, I will highlight serendipitous discoveries only possible thanks to the 3D nature of IFU data.

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What sets the stellar initial mass function ? Why is it so universal?

Stars are building blocks of our Universe. They determine its chemical evolution through nuclear synthesis, they host planets and they determine the evolution of galaxies. The characteristics of stars is predominantly determined by their masses. As such the stellar mass spectrum,  also called the initial mass function (IMF), is truly a fundamental quantity to understand how our Universe works. A large number of studies have been performed to infer the IMF and it appears strikingly universal. That is to say, even when measured in rather different environments, the IMF presents no or modest variations. This is an intriguing fact as naive expectations would naturally relate the mass spectrum of stars to quantities such as the Jeans mass which depends significantly on the gas density and gas temperature. During the talk I will review some of the ideas that have been proposed to explain the IMF and discuss their success and failure. I will then present a large sets of simulations in which the initial conditions, the thermodynamics and the numerical resolution are all systematically varied. These simulations reveal that the initial conditions determine the power-law part of the IMF while the gas effective equation of state (eos), which describe the isothermal to adiabatic transition, sets the peak of the stellar distribution. Analytical models are developed and compared with the simulation results. It is argued that the powerlaw part of the mass spectrum is due to an interplay between gravity and turbulence that determine the mass spectrum of gas reservoirs from which stars built their masses. The peak on the other hand, occurs at a mass which is 5-10 times the mass of the first Larson hydrostatic cores determined by the effective eos. We propose that the very reason of the IMF weak variability is that the first hydrostatic core and immediate surrounding collapsing envelope are small scale processes which are nearly independent of the large scale environment characteristics.  I will finish the talk by discussing remaining issues and suggests a possible "unifying picture".

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Early cluster evolution

Milky Way stars can be modelled as being formed as multiple systems, formed at the same time (monolithically) in spherical embedded clusters. Observational constraints imply these to be very compact with half mass radii rh/pc = 0.1(M/Msun)^0.13 and a wide range of stellar masses M (10 up to many millions of Msun). The derived radii are impressively consistent with the cross sections of molecular cloud filaments. These embedded clusters need to expand within a few Myr to achieve the radii of open and globular clusters and this can only be achieved by the expulsion of a significant amount of residual gas. The stellar-dynamical processes within the embedded clusters shape the multiplicity properties of Galactic-field stars and low-mass dwarf galaxies ought to have a much higher binary fraction than massive elliptical galaxies. Massive stars, formed in the mass segregated embedded clusters, eject each other efficiently from their birth clusters. These stellar-dynamical processes may be important for the emergence of multiple populations in embedded clusters which are not older than a few Myr by modulating infalling molecular gas into the cluster along molecular cloud filaments. They result in a field-population of runaway and slow moving O stars which is largely consistent with the observed isolated O stars. The Orion Nebula Cluster is discussed in particular.

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From dense cores to disks: Following the gas

A detailed understanding of star-formation is important to establish the "micro-physics" involved in the galactic star-formation relations, and also to determine the initial condition for proto-planetary disks. One of the important steps in the star-formation process is the accumulation of material from the molecular cloud with supersonic turbulence into the dense cores, which have subsonic turbulence. The first direct observation of the transition between supersonic and subsonic turbulence in a nearby cloud provided the first direct constraints on this dissipation process. On the other hand, recent observations have shown that large protoplanetary disks in the early stages are relatively rare, and for those that are large, there is compelling evidence for asymmetries related to gravitational instabilities. However, little is known of the connection between the disks and the parental dense core.In this talk, I will present some of our latest efforts on studying the dense core and molecular cloud connection, thanks to a large program at the Green Bank Telescope (~250hrs, PIs: Jaime Pineda and Rachel Friesen). This survey allows us to more accurately determine the dense core properties in a systematic fashion and across several clouds.  Also, I will present interferometric observations of dense cores that will provide new insight into the core formation and the material transport down to the scales relevant for disk formation.

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Ph.D. talks

Collimated outflows in Planetary Nebulae

Planetary nebulae (PNe) represent a highly evolved stage of low-intermediate mass stars (1 - 8 M⊙). Approximately 80% of PNe are asymmetric showing ellipsoidal, bipolar or multipolar morphologies, displaying tori, jets, knots, etc. A large fraction of PNe have collimated outflows moving at low or high velocities. In this talk, I will present a kinematic study of PNe with collimated outflows that can be clearly seen in an image. In addition, there is another group of compact PNe that their collimated outflows are not visible in an image but that can be detected from spectroscopic observations. In my Ph.D. thesis I proposed to call them “spectroscopic bipolar nebula”. Finally, the projects I will be working on in my first year of postdoc will be presented.

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The imprint of global hierarchical cloud collapse and stellar feedback on early star cluster evolution

It is well known that most stars form in groups or clusters, which in turn form from Molecular Clouds (MC), but it is still not clear how the structural properties of the clusters are affected by the feedback from their massive stars while they are still connected to their parent MCs. Here we present results from hydrodynamical simulations in which we study stellar cluster formation within a MC undergoing global hierarchical collapse, focusing on the effect of feedback from the photoionizing radiation from massive stars. We show that the feedback from the newly formed stars strongly affects the morphology and dynamics of the gas that continues to fall onto the cluster-forming clump. In particular, we find that the resulting stellar sub-clusters (or "groups") are more extended in simulations that include feedback than the ones obtained in control simulations without feedback, and that infalling motions of the stars forming in the periphery are reduced by this effect. In our simulations, triggered star formation appears to be the exception rather than the rule.

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Artificial Intelligence in astronomy and the real world: towards interpretable AI

In this talk I will present applications of Artificial Intelligence in astronomy and show the parallels to problems in Industry. I will discuss the importance of interpretable AI for physical sciences and introduce a new AI architecture I recently developed to explicitly introduce physical processes in Neural Networks.

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Connecting theory and observations of galaxy evolution with deep learning

In the last years, deep learning has rapidly emerged as a powerful and promising tool to process the data deluge we expect in the years to come. In my talk, I will illustrate recent efforts from our group to use both supervised and unsupervised deep learning to narrow the link between state-of-the art simulations and observations of galaxy formation. I will show how deep learning can be used to look for signatures in the data of physical processes defined by theory. I will also show how anomaly detection techniques can be employed to identify observed galaxy populations not well captured in the simulations.

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State-of-the-art diagnostics for detecting gravitational instabilities in galaxy discs

Gravitational instabilities play a primary role in shaping the structure and powering the star formation activity of disc galaxies. We review the effort made by theorists to provide the astronomical community with reliable disc stability diagnostics. The most well-known diagnostic is Toomre's Q parameter, but there are newer and more powerful tools for detecting gravitational instabilities in galaxy discs. And a few of them are almost as easy to use as Toomre's Q. In this talk, you will learn how to use such diagnostics in a variety of applications, including ISM turbulence at low and high redshift.

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Open questions on low surface brightness galaxies

I briefly summarize the most interesting and pending questions (personally biased) regarding low surface brightness galaxies. A special focus will be given to the most enigmatic class of this kind of galaxies: the giant low surface brightness galaxies. I will include results from observations and recent simulations.

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The hunt for Galactic black holes: from the most massive stars to low-mass stripped stars

Many dozens of gravitational-wave events emitted from the merging of stellar-mass black holes in the distant Universe have been recorded by the LIGO and VIRGO detectors over the past three years. These detections have rapidly sparked an international "hunt" for stellar-mass black holes in our own Galaxy, and great effort is dedicated for studying their progenitors: the most massive stars. Two of the sensational reports of late include the most massive stellar black hole ever detected (LB-1), and the nearest black hole to the Sun (HR 6819). These discoveries, however, were soon met with criticism and contradictory evidence, which in turn has revealed the existence of a new, short-lived phase of binary stars. After a broad overview, I will guide the audience through the current state of affairs in massive-star research. I will present recent sensational reports of stellar-mass black holes in the solar neighbourhood along with new evidence that challenges these reports. Finally, I will tie this to current massive-star research and our understanding of the evolution of massive stars and binaries.

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AGN and astronomy for development in Africa: Ethiopia as an example

Africa has amazing potential due to natural and human resources for scientific research in astronomy and space science (A&SS). At the same time, the continent is still facing many difficulties, and its countries are now recognizing the importance of astronomy, space science and satellite technologies for improving some of their main socio-economic and ecological challenges. Development of A&SS in Africa has grown significantly over the past years, and never before it was more possible to use astronomy for development as it is nowadays. Ethiopia is one of the countries that shares this vision, with motto that 'We explore the Universe for the benefit of our people'. Using Ethiopia as an example I will summarise the research that we are doing in the filed of active galactic nuclei (AGN), and other activities carried out for science, education and institutional development, and how through them we can fight poverty on the long term, and increase in future our possibilities of attaining the United Nations Sustainable Development Goals for the benefit of all.

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Galaxy evolution: an unbiased comparison of cosmological simulations and multi-wavelength observations

The formation and evolution of galaxies is one of the outstanding questions of modern astrophysics. While the cosmological paradigm is firmly established, our understanding of the baryonic physics processes that determine the variety of galaxies observed in the Universe is still rudimentary. Cosmological hydrodynamics simulations are an increasingly popular method to study galaxy formation and evolution. Whether the current simulations and their planned successors will succeed in identifying the drivers of the galaxy evolution depends on whether we can develop an unbiased methodology for the comparison between observations and simulations. Consensus is growing that a forward modelling approach, in which synthetic observations are generated that can directly be compared to observed data, is the way forward. Our team has developed such a framework, based on the 3D Monte Carlo radiative transfer code SKIRT, that can generate synthetic observables from UV to mm wavelengths for any cosmological hydrodynamics simulation. I will present the philosophy, ingredients and status of this framework, and its application to the EAGLE, IllustrisTNG and Auriga cosmological simulations. I will focus on scaling relations and luminosity functions in the UV and infrared, where the effects of interstellar dust attenuation and emission are crucial. I will discuss our current modelling successes and challenges, and the plans we have to improve our modelling and to identify the strengths and weaknesses of cosmological simulations.

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The He+ ionization problem in star-forming galaxies

Modern 3-D spectroscopic techniques allow mapping of ionized nebulae in multiple emission lines simultaneously. These techniques not only help to study the ionization structure of nebulae, but also to calculate the budget of hydrogen and helium ionizing photon rates. In a recently published work, we addressed these two issues by carrying out a case study of a massive superstar cluster and its surrounding nebula in a nearby irregular galaxy NGC1569 using MEGARA at the Gran Telescopio Canarias. We traced the doubly ionized helium ion from a giant arc of size more than 150 parsec. This arc is also traced in the hydrogen recombination lines. The massive cluster is found to harbour 124 Wolf-Rayet (WR) stars. The observed number of WR stars agrees very well with the number of such stars required in population synthesis models to provide the hard photons for ionizing He+. WR stars, through their powerful winds, are also responsible for creating a 40 parsec radius hole in the ionized gas around the massive cluster. We find negligible contribution to the ionization of He+ from shocks or X-ray photons from hard binaries.

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Regularly spaced 8 micron cores as tracers of the earliest stages of star formation in the spiral arms of nearby galaxies.

Archival Spitzer Space Telescope images of most nearby spiral galaxies show prominent 8 micron emission cores when viewed with an unsharp mask technique. These cores have the IR colors of young star-forming regions, typically a million years old, behind several tens of magnitudes of optical extinction. They are usually invisible in optical images, and yet the sum of their masses divided by their likely age is comparable to the total star formation rate in the galaxy. This suggests they are the earliest stages of star formation. They are often distributed in a regular fashion along the long dust filaments and spurs of spiral arms, suggesting they form by gravitational instabilities in shock-compressed gas.

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The properties of interstellar dust - a new tool for investigating galaxies and their evolution

Over the last decade, it has become clear that there are strong radial variations in the properties of interstellar dust within galaxies and that there are variatiations between galaxies in the global properties of the dust. I will describe attempts to understand the reasons for these variations using observations of the Andromeda Galaxy made with the Herschel Space Observatory. I will also present the first images of Andromeda from a new submm survey of Andromeda being made with the James Clerk Maxwell Telescope (JCMT), one of the goals of the survey being to produce the first atlas of interstellar dust in a galaxy. I will then describe some attempts to use the global properties of the dust in galaxies to investigate galaxy evolution, using the deep submm cosmological surveys that are being made with the JCMT.

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Congreso Nacional de Física

The IR luminosity function and dust-obscured star formation in the last 13 billion years.

The majority of the star formation activity in the Universe during the past 10-11Gyr, back to z~2.5, is primarily enshrouded by dust. However, although the history of cosmic star-formation has been thoroughly mapped at UV/optical wavelengths out to z~11, FIR/submm surveys have not kept apace. Consequently, the total amount of star formation that is absorbed and re-emitted by dust at high redshifts remains highly uncertain. During this talk, I will introduce the Mapping Obscuration to Reionization ALMA (MORA) Survey, the first interferometric blind map at 2mm covering ~180 sq. arcmin. By combining our new 2mm number counts with the state-of-the-art galaxy number counts at other wavelengths, we constrain the dust-obscured star formation up to z~6.5, completing the picture of the shape of the cosmic star formation rate density out the earliest epochs. Does dust-obscured star formation still dominate during the early Universe? Our best answer to this question will be presented.

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Exploring Mars with 150,000 Earthlings

Planet Four (http://www.planetfour.org) and Planet Four: Terrains (http://terrains.planetfour.org) are citizen science projects mining Mars Reconnaissance Orbiter (MRO) images to explore how the south pole of Mars is sculpted by the never-ending cycle of freezing and thawing of exposed carbon dioxide ice. In the summer, carbon dioxide jets loft dust and dirt through cracks in the thawing carbon dioxide ice sheet to the surface where winds blow the material into the hundreds of thousands of dark fans observed from orbit. Planet Four enlists over 136,000 volunteers to map the sizes, shapes, and orientations of these fans in high resolution images. Planet Four is creating an unprecedented wind map of the south pole of Mars in order to probe how the Martian climate changes over time and is impacted year to year by dust storms and other global-scale events. Planet Four: Terrains, aims to study the distribution of the jet process across the south pole and identify new targets of interest for MRO. Over 12,000 people have helped identify the channels and pits (dubbed araneiforms) carved during the jet formation process. In this talk, I'll give an overview of Planet Four and Planet Four: Terrains and present the latest results from these projects

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Similarities and differences between low- and high-mass star formation

Star formation is a key astrophysical process. At small scales, it governs the settling of planetary systems, and the complex chemistry allowing the emergence of life. At large scale, star formation controls the energy budget of galaxies. Our knowledge about star formation is both extensive and extremely coarse. On the one hand, we know well the different steps that lead from a molecular cloud to a single star, but, on the other hand, the physical processes behind those steps are, at best, debated. Building on the empirical scenario, I will review some key physical processes and show the differences/similarities between low-mass, and high-mass star formation.

The edge of darkness: making sense of structure formation with the splashback radius

The size, mass, and evolution of dark matter halos impact virtually all areas of structure and galaxy formation. These properties are conventionally defined using somewhat arbitrary spherical overdensity radii, largely because halo profiles are thought not to have a well-defined edge. Over the past years, we have shown that halos do have such an edge: the splashback boundary, which has since been detected in a number of galaxy surveys. Redefining halo properties based on this boundary has profound consequences for numerous problems in structure formation and facilitates a new understanding of the dynamical nature of halos. In this talk, I will introduce the tools necessary to make this transition. I will introduce an analysis framework that follows the dynamics of billions of particles in cosmological simulations, and present a new suite of publicly available halo catalogs for the exploration of halo definitions. First results based on this dataset include that the splashback halo mass function is remarkably universal and that the abundance of subhalos (or satellites) is drastically changed. These results open a window on the possibility of using future observations of the halo outskirts to constrain the galaxy-halo connection, cosmology, and the nature of dark matter.

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The role of active galactic nuclei on galaxy evolution.

The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important information on the feedback that nuclear activity produces on the galaxy. In this talk I will summarize our current view of the close (pc-scale) and intermediate (kpc-scale) environment of accreting supermassive black holes obtained from studies of local active galactic nuclei carried out in the infrared and sub-mm regimes.

Star formation quenching (and boosting): which role for the black hole?

Understanding what are the mechanisms responsible for transforming star forming galaxies into passive systems is one of the most active areas of research in astrophysics. I will present multi-band observational data illustrating that black hole accretion is the main driver of galaxy quenching. However, gas expulsion by quasar-driven outflows (the so-called "ejective mode") seems not to be an effective mechanism for suppressing star formation. Instead, the main process through which black holes quenche star formation in their host galaxies is primarily through the heating of the galactic halo, which prevents further accretion of fresh gas, and therefore resulting in a delayed star formation quenching as a consequence of "starvation". I will also illustrate that quasar-driven galactic outflows can also have a postive feedback effect on their host galaxies. More specifically, I will show evidence that stars can form inside molecular galactic outflows. This new mode of star formation can have important implications for galaxy evolution and, in particular, can contribute significantly to the growth of the spheroidal component of galaxies.

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Violencia de Género en la Academia (Día Internacional de la Eliminación de la Violencia Contra la Mujer)

De Geoffry Marcy a Ranulfo Romo, la complicidad de la comunidad en la violencia en contra de las mujeres en los espacios académicos. En el 2015 se hizo público que Geoffry Marcy, investigador de la universidad de California en Berkeley, estaba bajo proceso por acoso sexual. Marcy era uno de los más famosos investigadores en el área de exoplanetas y finalmente fue jubilado de la universidad después de perder del apoyo de sus colegas. Ranulfo Romo era la estrella de las neurociencias en México, a principios del 2020 se supo que estaba acusado de intento de violación y finalmente se anunció su retiro de la actividad académica en la UNAM. Ambos casos tienen algo en común, durante años sus comunidades supieron de su conducta. Se les aconsejaba a las estudiantes no trabajar con Marcy o con Romo pero ante el acoso la comunidad guardaba silencio. Fue después de ser acusados públicamente que comenzaron a salir a luz esas historias que "todos sabían" pero que nadie denunció. En este charla hablaré del impacto del acoso sexual, académico y laboral en contra de las mujeres en la academia y cómo las comunidades académicas somos fundamentales para prevenir y erradicar estas violencias, utilizando como ejemplos los casos de Marcy y Romo.

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Confirming the Explosive Outflow in G5.89 with ALMA

The explosive molecular outflow detected decades ago in the Orion BN/KL region of massive star formation was considered to be a bizarre event. This belief was strengthened by the nondetection of similar cases over the years with the only exception of the marginal case of DR21. Here, we confirm a similar explosive outflow associated with the UCHII region G5.89−0.39 that indicates that this phenomenon is not unique to Orion or DR21. Sensitive and high angular resolution (~0.1'') Atacama Large Millimeter/submillimeter Array (ALMA) CO(2−1) and SiO(5−4) observations show that the molecular outflow in the massive star-forming region G5.89−0.39 is indeed an explosive outflow with an age of about 1000 yr and a liberated kinetic energy of 10^46-49 erg. Our new CO(2−1) ALMA observations revealed over 30 molecular filaments, with Hubble-like expansion motions, pointing to the center of UCHII region. A simple estimation for the occurrence of these explosive events during the formation of the massive stars indicates an event rate of once every ~100 yr, which is close to the supernovae rate.

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Simultaneous Evolution of the Energy Budget and the Star Formation Rate in Dense Clumps Under Global Hierarchical Collapse

Our recently proposed paradigm of global hierarchical collapse (GHC) for molecular clouds and their substructures is a regime in which molecular clouds (MCs) are undergoing global gravitational contraction, and gravitational collapse later sets in at smaller scales within the MCs as the global Jeans mass decreases due to the collapse. When a substructure within a cloud (a "clump") begins its own collapse, it starts from zero initial infall velocity and approaches the free-fall speed v_ff. In addition, it contains residual amounts of turbulence. This determines the evolution of the clump's "virial parameter" alpha and the so-called "Larson ratio" L = sigma_v/R^1/2, where sigma_v is the turbulent+infall nonthermal velocity dispersion and R is the clump's radius, in the "Heyer diagram" of L vs. Sigma, where Sigma is the clump's column density. Simultaneously, the clump evolves from a non-star-forming state to an active star-forming one. In this talk, I will discuss the simultaneous evolution of the virial parameter, the Larson ratio and the star formation rate (SFR) of clumps in a numerical simulation of MCs evolving under GHC, showing that the dense clumps may initially appear subvirial while their infall speed is less than v_ff, in agreement with recent observations, and that their SFR monotonically increases with time as long as stellar feedback does not destroy the clumps. I will also discuss comparisons with the clumps in the simulation to clumps in two MCs believed to be in different evolutionary stages, the Pipe and the G14.225 IRDC, showing that the simulation clumps evolve from having values of the virial parameter and the Larson ratio comparable to those of the Pipe at early times to values comparable to those of G14.225 roughly 2 Myr later.

Out on a Limb: UV Emission from the Asymptotic Branch

Mass loss dominates stars on the asymptotic giant branch (AGB). Circumstellar shells of enriched material, fed by the mass loss, reprocess stellar light resulting in cool and luminous stars with ample emission longward of optical. As a result, ultraviolet and X-ray emission are not expected from AGB stars, but can originate from binary companions. Taking advantage of the nearly all-sky UV surveying capabilities of the Galaxy Evolution Explorer (GALEX), we have now established that most, if not all, AGB stars do emit in the UV. The origin of the UV emission is unclear; evidence exists for binary origins in some stars and intrinsic origins (photospheric, chromospheric and/or wind shocks) in others. I will review the UV properties of AGB stars and consider the evidence for binary and intrinsic origins.

Approaching the dark sector through a bounding curvature criterion.

Understanding the observations of dynamical tracers and the trajectories of lensed photons at galactic scales within the context of General Relativity (GR) requires the introduction of a hypothetical dark matter dominant component. The onset of these gravitational anomalies, where the Schwarzschild solution no longer describes observations, closely corresponds to regions where accelerations drop below the characteristic a0 acceleration of MOND, which occur at a well-established mass-dependent radial distance, Rc ∝ (GM/a0)1/2. At cosmological scales, inferred dynamics are also inconsistent with GR and the observed distribution of mass. The current accelerated expansion rate requires the introduction of a hypothetical dark energy dominant component. We here show that for a Schwarzschild metric at galactic scales, the scalar curvature, K, multiplied by (r4/M) at the critical MOND transition radius, r = Rc, has an invariant value of κB = K(r4/M) = 28Ga0/c4. Further, assuming this condition holds for r > Rc, is consistent with the full space-time which under GR corresponds to a dominant isothermal dark matter halo, to within observational precision at galactic level. For an FLRW metric, this same constant bounding curvature condition yields for a spatially flat space-time a cosmic expansion history which agrees with the ΛCDM empirical fit for recent epochs, and which similarly tends asymptotically to a de Sitter solution. Thus, a simple covariant purely geometric condition identifies the low-acceleration regime of observed gravitational anomalies, and can be used to guide the development of extended gravity theories at both galactic and cosmological scales

Investigating the grain growth in a protoplanetary disk by millimeter-wave polarization

The interpretation of polarization of protoplanetary disks at millimeter wavelengths has been dramatically changing. As a direct extension of polarization in star-forming regions, it has been thought that non-spherical dust grains aligned with magnetic fields would produce the intrinsic polarization in protoplanetary disks as well. However, it is pointed out that dust scattering can also produce polarization. Furthermore, even the direction of the alignment might not be determined by magnetic fields but by radiation fields. Recent ALMA observations have shown that both of the theories are at work in protoplanetary disks. Furthermore, the scattering-induced polarization suggests that grain size is not as large as millimeter but 100 micron, which is a crucial constraint on planet formation. I will review these recent theoretical and observational developments of millimeter-wave polarization in protoplanetary disks and discuss what we can learn from the polarization observations.

Warps in transition disks

Warps or inclination changes as a function of radius have often been invoked to explain protoplanetary disk observations. Well characterised examples can inform on the origin of such warps, on their role in disk evolution, and may allow for new probes of physical conditions. In transition disks, the separation of the inner and outer disks by a radial gap allows firm constraints on warp geometry. There are now 4 examples of sharply warped transition disks, in which the outer disk is directly exposed to stellar light. In a couple of examples the temperature drop of the gas under the shadowed regions has been detected. Along with a description of the known warped systems, I will present a diagnostic of the outer disk mass based on the cooling timescale of the shadowed gas.

Tidal breakup of binary stars by supermassive black holes

When a binary stellar system ventures too close to the supermassive black hole that resides at the center of every galaxy, the intense tidal field due to the latter can split up the binary. In a typical encounter, one of the stars becomes bound to the central black hole while the other is ejected out of the system with a kick velocity of the order of ~ 1000 km/s. In this talk, I will review a proposed model in which this mechanism can naturally account for two peculiar stellar populations in our galaxy: the S-stars at the galactic center and the hypervelocity starts in the galactic halo. Finally, I will present the outcome of recent general relativistic, numerical simulations of binary tidal breakups that systematically explore the vast parameter space that characterizes these encounters.

AGN torus detectability at submm wavelengths

In this talk we will show you a study on the detectability of the emission associated with the Active Galactic Nuclei (AGN) dusty structure at sub-mm wavelengths in the era of ALMA. We hack this issue with a theoretical and observational approach considering three typical ALMA frequencies/wavelenghts (100GHz/3000μm, 353GHz/850μm, 666 GHz/450 μm). Theoretically, we use the Clumpy models from Nenkova et al. together with the mid-infrared to X-ray and the radio fundamental plane scaling relations. The latter scaling relation was included since a no negligible contribution at sub-mm wavelength may come from synchrotron emission of the AGN radio jets. The theoretical approach results in the more likely detection of big and dense dusty tori at the highest ALMA frequency (666 GHz/450 μm). Observationally, we use four prototypical AGN: NGC 1052, NGC 1068, NGC 3516, and IZw1, with radio, sub-millimeter, and mid-IR available data. After performing the mid-IR and radio spectrum fitting alone, we combined and extrapolated both fits in order to compare the extrapolation of both torus and jet contributors at sub-mm wavelengths. Our observational results are consistent with our theoretical results. The most promising candidate to detect the torus is the QSO IZw1, although it cannot be resolved due to its large distance. In order to explore the detection of a torus at sub-mm wavelengths, we suggest to perform a multifrequency SED analysis including also radio data.

Searching for, and analyzing low-mass stars and BD.

I will show the on-going analysis of NaCo/VLT data (Ks band polarimetry) of Sz91, a young (~2 Myr), transitional disk around an M1 star located in the Lupus III star-forming region. This object has one of the largest inner cavity observed in a disk around a T Tauri star (~100 au; Canovas, Schreiber et al. 2015) estimated from ALMA. The mm-size grains are concentrated in a narrow (~44 au width), ring-like structure. The micron-sized dust grains probed by our near-IR observations with NaCo lie inwards of the mm ring: a clear example of dust filtering. Our preliminary results suggest that the dust grains responsible for the polarized emission are porous (>60%), small (< 3 microns), silicate grains. With our new L-band observations (also acquired by our group), we are able to rule out the presence of very massive giant planets inside the cavity. I will also present the work in progress in the search for sub-mm cold cores that can harbor pre- and proto-BDs candidates in LDN1589, one of the most active star-forming clouds in the Lambda Ori Star-forming region. For this, we carried out 870-micron continuum observations of the dark cloud using APEX/LABOCA bolometer array. We have detected a few potential candidates (with S/N >= 4) of cold cores in the data. I’m currently doing the crossmatch of the detections with catalogs at different wavelengths in order to characterize the spectral energy distribution of the detected sources and to estimate their properties (e.g. bolometric luminosity) to discriminate if these are indeed pre- and proto-BDs. With this result at hand, we plan to propose sensitive ALMA observations to study dynamic signatures of the cores to confirm their sub-stellar origin.

Search for Massive stars in M81 using GTC: 7 new Wolf--Rayets, analysis and classification of the total sample

Wolf-Rayet (WR) stars are related to some of the most exotic and interesting astronomical objects in the Universe, e.g. the most massive stars, binaries, supernova explosions, compact objects, Gamma Ray Bursts and gravitational waves. We here report the detection of seven new WR star locations in M81 using the Multi-Object Spectrograph of the OSIRIS instrument at the 10.4-m Gran Telescopio Canarias. In this work, we analyse the entire sample of 21 spectra to specifically identify spectra that correspond to individual WR stars of one of the known sub-types. For this purpose, we explore a variety of independent methods of classification and analysis. We find 18 of our 21 detections are associated to individual stars of sub-types WNL, WNE, WCE and transitional WN/C. Our study makes M81 the farthest galaxy with individual WRs reported, thus providing a new environment for testing the massive star evolutionary models.

Initial Mass Function and Kinematics of 25 Orionis

Star formation is a complex process that can occur over a wide range of scales. To better understand this process it is important to study the stellar initial mass function (IMF) and the kinematics of stellar groups. An excellent laboratory to carry out this kind of studies is 25 Orionis (25 Ori). Combining new deep optical photometry from DECam with optical and NIR data from the literature, we selected 1687 member candidates of 25 Ori. With this sample we derived the system IMF of 25 Ori from 12 Mjup to 13.1 Msun, which is one of the few IMFs across the whole mass range of a stellar group. The resultant system IMF is well-described by a two-part power-law function and by a tapered power-law form. We also report its best lognormal parameterization. This system IMF do not present significant variations within a radius of about 7 pc, which indicates that the substellar and stellar objects in 25 Ori do not have any preferential spatial distribution. We compared the reported system IMF as well as the substellar/stellar ratio with those of a large diversity of stellar populations and did not find significant discrepancies, which strongly supports the hypothesis that the star formation mechanism is largely insensitive to environmental conditions. Also, I present the current status of a spectroscopic survey to confirm the membership of each candidate using several world-wide facilities (GTC/OSIRIS, SDSS-III/BOSS, MMT/Hectospec, SDSS-IV/APOGEE-2 and OAN-SPM/MES). So far the survey is 75% complete and we have confirmed 530 members. With this sample of members we estimated the parameters of 25 Ori (mean values of distance, visual extinction, age, radial velocity and proper motion as well as the velocity dispersion, total mass and stellar density). Using these parameters we found that 25 Ori is a dynamically young group that is gravitationally unbound. (These are the main results of my PhD thesis project)

Dynamical dispersion of a young cluster via gravitational feedback

Photodissociation bubbles are common features in the interstellar medium. They can be easily detected as ring-like structures in line emission maps tracing either neutral atomic or molecular hydrogen. One particularly clear case is in the $\lambda$-Ori region, which exhibits a quite symmetric, 20 pc radius ring that has been previously interpreted as to be the result of the expansion of a supernova explosion between ~1-2 Myr ago. Recently, high precision proper motions of stars in this region became available through the second data release of Gaia, which showed that the projected velocity vectors of $\lambda$-Ori stars tend clearly to point away from the center of the ring/bubble, as could be expected for an open cluster that it is breaking apart. Moreover, the data suggest that stars located farther from the center of the ring/bubble have faster (or larger) proper motions.This lead us to propose a different scenario for the formation of the $\lambda$-Ori bubble and its proper motions: In the present contribution we used numerical simulations to show that, while at the beginning, stellar clusters are formed in a collapsing environment and the stars are drawn to each other due to the gravity of the cloud, later the feedback from the newborn massive stars in these clusters expels the gas from the center, creating a cavity and moving the potential well away from the center of collapse. Since neither the formed shells nor the parental clouds are symmetric, a net force pulling out the stars is present, accelerating the stars towards the edges of the cavity. In this way, we propose that gravity from the expelled gas appears to be the crucial mechanism producing unbound clusters that expand away from their formation center. This mechanism has not been considered before, mainly because in previous simplified models the gravitational potential was usually one of an empty, homogeneous sphere, which is constant, and thus no net force is expected to act over the clusters embedded in a shell structure.

Star Formation in Crowds - Star formation changes with environment, and high mass stars define the neighborhood

Star formation is the defining process in the evolution of galaxies. Our present understanding of star formation has primarily been informed by low-mass stars in nearby clouds, but these nearby regions do not reflect typical conditions over the history of the universe. The denser and more crowded regions that represent our own origins exist within our Galaxy, and ALMA allows us to explore these regions in ways previously impossible. I will show that high-density regions preferentially form clusters over isolated stars. In these dense, clustered regions, the stellar initial mass function (IMF) is governed by feedback from high-mass stars, which we demonstrate using ALMA to measure gas properties and identify individual protostars. Protostar-counting measurements provide tests of star formation theories, and they show evidence that star formation density thresholds vary with environment. These measurements can be repeated throughout the Galaxy to provide strong constraints on the formation of the IMF, which will be achieved by the recently-begun ALMA-IMF large program.

Restarting activity in the nucleus of Giant Radio Galaxies

Giant radio galaxies (GRG) are defined as those active galactic nuclei (AGN) whose radio morphology show linear extended emission above 0.7 Mpc. The lobes in these galaxies can be as old as 10^8 years, whereas the AGN activity can be reactivated within 10^4-8 yrs, thus GRG are perfect laboratories to study AGN evolution and restarted activity. The usual way to find restarting activity is through the radio morphology, where different phases of nuclear activity can be observed in the same dataset. However, we might be missing a fraction of restarting activity in galaxies because we are not able to detect the earliest phase where the new jets have recently formed and are not visible in the radio band. In this seminar I will focus on two cases of restarted activity on early phases, namely PBC J2333.9-2343 and Mark 1498. These sources were selected on a hard X-ray basis and we performed multiwavelength analyses in order to gain information of different emitting regions and to have the most comprehensive view of their nuclei.

The gravitational disk-satellite interaction: Migration and circularization of orbits

In many astrophysical systems, perturbers embedded in gaseous disk migrate due to the angular momentum transfer with the disk (e.g., protoplanets, black holes, globular clusters). I will discuss the different regimes that arise in the problem of the interaction between a gravitational body and a gaseous disk, for both prograde and retrograde orbits. Then, we will focus on the linear case, and compare the migration and circularization rates derived in the local approximation with those found in numerical simulations. We will discuss under what conditions the local approximation provides accurate estimates.

The globular cluster system of NGC 4258: a relic of cosmic high noon?

We present multi-object spectroscopic observations of 23 globular cluster candidates (GCCs) in the prototypical megamaser galaxy NGC 4258, carried out with the OSIRIS instrument at the 10.4 m Gran Telescopio Canarias. The candidates have been selected based on the (u* - i') versus (i' - Ks) diagram, in the first application of the \uiks\ method to a spiral galaxy. In the spectroscopy presented here, 70% of the candidates are confirmed as globular clusters. Our results validate the efficiency of the \uiks\ method in the sparser GC systems of spirals, and given the downward correction to the total number of GCs, the agreement of the galaxy with the correlations between black hole mass, and total number and mass of GCs is actually improved. We find that the metal-poor GCs co-rotate with the HI disk, even at large galactocentric distances. The ratio of rotation to velocity dispersion V/sigma of the system is ~ 1, consistent with the highly turbulent, rotating disks at z>=2 that constitute nowadays the favored environment for the formation of globular clusters. This system could be a z = 0 relic of this process.

Polarimetric studies and magnetic fields in intermediate mass evolved stars.

Magnectic fields are known to be extremely relevant at various stages of stellar evolution. Indeed, several investigations have focused on the role of those fields during stellar formation (e.g. molecular clouds) and in evolved massive stars ( e.g. SN). The detection and analysis of magnetism in the short period (~10,000 yrs) corresponding to the advanced evolutive phase of intermediate mass stars, namely post-AGB and Planetary Nebulae, is less known. I will present a review of the investigations realised so far, with a focus on the most recent observational and theoretical results. In order to better tackle this issue, we also formed a group dedicated to polarization studies and composed of several researchers from various national institutions. I will then present the different activities ( i.e. instrumentations and observations) of the group.

First results of the Event Horizon Telescope: image of the supermassive blackhole at the center of M87

El Telescopio de horizonte de eventos (EHT, por sus siglas en ingles) es un instrumento que combina una decena de telescopios repartidos en toda la Tierra y permite reconstruir imágenes en la banda milimétrica del espectro electromagnético con una resolución angular (del orden de 25 micro-segundos de arco) muy superior a la de cualquier otro instrumento astronómico. El 10 de abril de este año, se anunciaron los primeros resultados de este instrumento: una imagen del entorno del agujero negro supermasivo en el centro de la galaxia Messier 87 que muestra una depresión central interpretada como la sombra producida por al agujero negro mismo. En esta charla, describiremos el instrumento EHT, la técnica que utiliza, y el tratamiento de datos que permite reconstruir imágenes con este instrumento. Después, describiré la imagen de M87 obtenida, así como su interpretación en términos de modelos de magneto-hidrodinámica en el contexto de la relatividad general (GR-MHD). Terminare con unas perspectivas a futuro.

Neutron Star Equation of State after the GW170817 event

In this talk I will review the method of estimation of tidal deformabilities of compact stars and present results for pure hadronic as well as hybrid stars that include the mass twins case. Then I will discuss the impact of the nuclear symmetry energy in the determination of the compact star radius. In particular, the recent detection of gravitational radiation from the GW170817 event shed light on the properties of the neutron star equation of state (EoS), thus comprising both the study of the symmetry energy and stellar radius. Furthermore, I shall address the question of the possibility of a universal symmetry energy contribution to the neutron star equation of state under restricted Direct Urca cooling. When these two aspects are combined, powerful predictions for thestiffness of the neutron star EoS are obtained. Furthermore, I will focus on the case of mass twin compact stars, hybrid compact stars with approximately the same masses but different radii.To qualify the above, I will show a recent developed EoS that features of a color superconducting chiral quark model with nonlocal, covariantinteractions bearing density dependent vector meson coupling and a density-dependent bag pressure. This model allows for a scenario where thecompact stars of the GW170817 event are either both hadronic, both hybrid, or simultaneously hadronic and hybrid configurations.

Hot and cool gas around Wolf-Rayet stars

Las estrellas Wolf-Rayet (WR) son descendientes de las estrellas masivas que se encuentranen etapas finales de su evolución, justo antes de explotar como supernovas. Debido a susfuertes vientos, éstas estrellas chocan, comprimen y calientan el material circunestelar creandolas llamadas nebulosas WR. En combinación con sus potentes flujos de fotones ionizantes, las estrellas WR son capaces de crear un medio multi-fase que puede ser estudiado a travésde observaciones multi-frecuencia. En esta charla presentamos nuestros resultados del estudiodel material caliente emisor de rayos X y del polvo detectado con observaciones IR.

Hierarchical gravitational collapse: the mechanism and implications for collapse timescales, cloud ages, the SFR, and cluster structure.

Diverse numerical and observational evidence suggests that star-forming molecular clouds (MCs) may be in a process of global hierarchical contraction (GHC). As originally proposed by Hoyle (1953), in such a regime, a sequential destabilization of successively smaller masses should occur, leading to fragmentation of the cloud and ultimately to the formation of stellar-mass objects, when the equation of state diverts from isothermal. Early objections to the global gravitational contraction of MCs do not necessarily hold in the light of our modern understanding of turbulence and the structure of MCs. In this context, I discuss how the HGC mechanism implies a nearly pressureless collapse of mMCs and an initial acceleration of the star formation activity. These features naturally explain the ubiquitous formation of filamentary structures that funnel material to so-called "hubs", the observed morphology of the magnetic field around the filaments, the scattered nature of low-mass star-forming regions, the observed SFR-mass relations at both the local (cloud) level and the global (galactic) level, and the structure of the embedded stellar associations, such as their fractal structure and the observed radial mass and age gradients, as well as their stellar-age histograms.

Enfrentando la Complejidad de la Movilidad Urbana

Los problemas de movilidad urbana nos afectan a todos. Si no hacemos nada, seguirán empeorando. Tiempos de traslado, contaminación, pérdidas económicas, impacto a la salud: todos reducen nuestra calidad de vida. ¿Cómo es que no hemos podido mejorar la movilidad más rápido de lo que empeora? Mi respuesta es: porque no hemos comprendido la complejidad de la movilidad. Usamos técnicas tradicionales, las cuales son adecuadas sólo para problemas "estacionarios". Pero las interacciones inherentes a la complejidad de la movilidad urbana generan cambio impredecible, que llevan a problemas "no estacionarios". ¿Cómo enfrentar esta complejidad? Con adaptación. Esta puede lograrse por medio de la auto-organización. Presentaré dos ejemplos: en la coordinación de semáforos y en regulación de transporte público.

The radio/submm view of massive, deeply embedded clusters in our Galaxy

I will present recent observational and modelling results that tackle the following important issues on star-cluster formation: i) The diversity of massive, cluster forming clouds, and a possible origin for it. ii) Evidence for gas accretion from GMC ($\sim 50$ pc) to disk ($< 1000$ au) scales. iii) The first censuses of the stellar populations in formation, i.e., YSO counting in massive protocluster clouds. iv) The effects of feedback from massive YSOs on their natal cores and clumps.

La evolución de estrellas masivas y el curioso caso de HD 5980.

HD5980 es un sistema múltiple ubicado en la Nube Menor de Magallanes. Su componente principal es un sistema binario eclipsante, excéntrico, con un período orbital de 19.3d, y masa total de aproximadamente 120 M_sun. Ambas parecen ser estrellas Wolf-Rayet, y sus propiedades sugieren que son el producto de evolución con mezclado muy eficiente. Es decir, las trazas evolutivas que mejor las describen corresponden a los modelos de Quasi-chemically homogeneous evolution, QCHE calculados por el grupo de Bonn. Las trazas de QCHE resultan de un mezclado casi completo del material nuclear con el de las capas externas de la estrella. En los modelos estandard, este mezclado se logra únicamente si la estrella rota muy rápidamente durante gran parte de su vida. En esta charla hablaré sobre un posible mecanismo alternativo en sistems binarios como HD5980, basado en el tipo de rotación diferencial inducida por las fuerzas de marea.

Comparing the pseudo-complex General Relativity with the EHT observation

The motivation for a pseudo-complex General Relativity will be given and the main structure will be resumed. Simulations of a thin accretion disk are presented and compared to the observation of the black hole in M87 by the EHT collaboration. Some problems are discussed.

Effects of scattering on the emergent intensity of protoplanetary disks and their apparent 7 mm excess

Dust scattering can be a very important opacity source in protoplanetary disks observed at radio wavelengths with ALMA and VLA. However, scattering is usually neglected in analysis of multi-wavelength observations because it increases the complexity of Monte Carlo simulations and is time consuming. In this talk, I present an analytical solution of the emergent intensity of a vertically isothermal face-on disk, taking into account the scattering in the radiative transfer equation. The emergent intensity with scattering modifies the spectral indices compared with that of the non-scattering emission. The shape of the spectral energy distribution is also modified, depending on the disk inclination in the plane of the sky which increases with the optical depth. Finally, we used the scattering effects to give an alternative explanation to the observed excess emission reported at a wavelength of 7 mm in several disks. These results were recently implemented to explain the radial dust distribution in the HL Tau disk.

Regreso a Orión

Orion is the region of massive star formation closest to the Sun and in consequence it has been studied in detail. I will present three recent results from the IRyA group on this region. The first one is the ultraprecise determination of the distance to Orion using VLBI observations of stars with non-thermal emission. The second result is a study of the kinematics of the stars with either termal or non-thermal emission. Finally, we will focus on the extraordinary “explosion” that seems to have taken place in the Orion BN/KL region. Not only the molecular gas but also several stars are receding from a point in common with velocities of hundreds of km/s for the gas and of tens of km/s for the stars. We will present the most recent data on the proper motion of the stars and discuss the models that have been proposed to explain this phenomenon.

HII Galaxies as Cosmic Laboratories

We present new high spectral resolution observations of 15 high-z (1.3 ≤ z ≤ 2.5) HIIG obtained with MOSFIRE at the Keck Observatory. These data, combined with already published data for another 31 high-z and 107 z ≤ 0.15 HIIG, are used to obtain new independent cosmological results using the distance estimator based on the established correlation between the Balmer emission line velocity dispersion and luminosity for HIIG. Our results are in excellent agreement with the latest cosmological con- cordance model (ΛCDM) published results. From our analysis, we find a value for the mass density parameter of Ω_m = 0.290 + 0.056 - 0.069 (stat). For a flat Universe we constrain the plane {Ω ; w } = {0.280 + 0.130 - 0.100; −1.12 + 0.58 - 0.32} (stat). The joint likelihood analysis of HIIG with other complementary cosmic probes (Cosmic Microwave Background and Baryon Acoustic Oscillations) provides tighter constraints for the parameter space of the Equation of State of Dark Energy that are also in excellent agreement with those of similar analyses using Type Ia Supernovae instead as the geometrical probe.

Comparing SPS models in resolved nearby disk galaxies

The dust component affects the measurements of galaxy properties since dust absorbs and re-emits the starlight from the UV and the optical radiation. The latter process enables the prediction of the emission of radiation at infrared-submillimeter-radio wavelengths, by fitting evolutionary stellar population synthesis (SPS) models to observed UV-optical-NIR observations and assuming a dust emission model. Nevertheless, the predictions depend on the choice of the SPS model, e.g., Bruzual and Charlot (2003), or the Maraston (2005) models. This is mainly due to the different treatments of the thermally pulsing asymptotic giant branch (TP-AGB) phase of stellar evolution. Comparisons of the SPS models with resolved (e.g., pixel-by-pixel) observations (at optical and NIR wavelengths) can be used to discriminate between models. We will show the results of these comparisons to a sample of nearby disk galaxies.

A 40 Billion Solar Masses Black Hole in Holm 15A: The End of the Bonfini vs. López-Cruz Controversy?

We have embarked on the search for ultramassive black holes (UMBH), those whose mass is larger than 10 billion solar masses. I discuss the reliability of different BH mass indicators, followed by discussion of Holm 15A and IC 1101 a plausible candidates to hosting UMBH, I will spice the talk with my own take on the recent controversies that have arisen regarding the core size (inner flattening of the surface brightness distribution) of those galaxies. I, then discuss the feasibility of IFU observations, which can help us to uncover dynamical constraints on the fusion of supermassive black hole binaries (SBHB) as a stage of UMBH formation. In 2014 I led an international team who suggested that the galaxy Holm 15A might host the most massive black hole in the nearby universe. Four months ago, a German team led by K. Merhgan, a graduate student, reported a BH mass of 40 billion solar masses for Holm 15A. This is the largest BH mass ever measured in the nearby universe.

Otros cielos, otros universos

Desde los albores de la humanidad podemos apreciar el interés del ser humano por observar y conocer el espacio celeste que siempre le ha rodeado. Al hacerlo el universo ha dado forma a su cultura y las diferentes culturas, incluida la nuestra, han visto el universo a través del filtro propio de su cultura. En este caso nos centraremos en la tradición astronómica meso y centroamericana que sigue vigente, a través de los pueblos originarios, por más de 15.000 años. A través de este viaje veremos cómo para cada pueblo el cielo es un espacio vivo donde se aúnan anhelos, historias y conocimiento, un lugar de encuentro que todos los seres humanos compartimos, el lugar que nos hace humanos

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Are Galaxy Triplets Physically Bounded Systems?

Galaxy triplets represent one of the most interesting laboratory in identifying the formation and the evolution of galaxies. Understanding such systems will give us clues about the construction of larger groups and clusters of galaxies. Towards that, we conduct a statistical study on 315 isolated triplet systems taken from the ¨SDSS-based catalog of Isolated Triplets¨ (SIT) to obtain their physical and dynamical parameters. Meanwhile, the correlation between the dynamical parameters of these systems and the Large-Scale Structure (LSS) have been presented. For further details about triplet systems and signs of interactions between their members, we applied surface photometry analysis and decomposition on nine galaxy triplets to declare their radial profiles and identify their fine structures. We found that triplet systems follow hierarchical structure in their formation and evolution. In addition, we found that signs of interactions are pronounced in systems with small projected separations between their members (rp < 0.3 Mpc).

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Variable hard X-ray emission fromwhite dwarfs and central stars of PNe

Single central stars of planetary nebulae (PNe) and isolated white dwarfs (WDs) can produce stable photospheric soft X-ray emission. Moreover shocks in the stellar winds of the central stars of PNe can produce stochastic harder X-ray emission. Therefore, the detection of modulated hard X-ray emission necessarily implies accretion or chromospheric emission from a companion. We will present in this talk two of the most notorious cases of hard X-ray emission from the central star of a PN and a WD. Since the presence of a chromospherically active dwarf companion can be unambiguously rejected, accretion processes need to be invoked. The implications for the nature of the unseen companions are surprising, ranging from a WD companion up to … a substellar companion.

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A search of protoplanets through Halpha observations

During their formation, young planets are surrounded by disks of gas and dust, the so-called circumplanetary disks. Several works have predicted that, as observed in young stars, protoplanets can accrete material from their disks and emit in accretion tracers like e.g. the Halpha emission line. This scenario has been recently confirmed with the detection of two young planets through Halpha imaging (PDS70bc). In this talk I will show preliminary results from a project to detect accreting protoplanets around young stars using SPHERE/ZIMPOL at the Very Large Telescope (VLT). I will discuss the sample, the observational strategy, and our main findings.

Spatially Resolved Spectroscopic Properties of Low-Redshift Star-Forming Galaxies

I review here the spatial resolved spectroscopic properties of low-redshift star- forming galaxies (and their retired counter-parts), using results from the most re- cent Integral Field Spectroscopy galaxy surveys. First, I present the global spec- troscopic properties of these galaxies, including their main ionization process, their star-formation rate, oxygen abundance, and average stellar ages and metal- licities. I show how they depend on galaxy morphologies and stellar masses. Second, I present the local distribution of the ionising processes, to the kilopar- sec scales, and the radial distributions of the surface densities of the properties explored globally, and how they depend on the integrated galaxy properties. Third, I show how the global evolutionary relations found between integrated parameters (like the SFMS, MZR and SK-law) present local counter-parts, be- ing the global ones just integrated/average versions of them. Finally, I sum- marise all these result under the scenario of inside-out growth and quenching of galaxies, and how this latter process is related to the dynamical state of the galaxies.

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Estudio fotométrico espacialmente resuelto en galaxias HII con diferente morfología

The main goal of this study is to characterise the stellar populations in very low metallicity galaxies. We have obtained broad U, B, R, I, J, H, intermediate Strömgren y and narrow Hα and [OIII] deep images of three H II galaxies with different morphology. The stellar populations dominating the stellar cluster complexes (SCC) in the galaxies have been characterised by comparing the observed broad band colours with those of single stellar population models. The main results of this work are consistent with the galaxies containing an old extended component on top of which the young stellar populations are distributed, enclosed inside a luminous diffuse Ha emission. The spatial distribution of the SCCs and H II regions indicates that star formation in the three galaxies is more likely stochastic and simultaneous within short time scales. In the three galaxies the dominating stellar populations in the SCCs were characterized with a variety of ages ranging form 1 Myr to 10 Gyr. Some of them are candidates to contain Wolf-Rayet clusters and 11 of them were identified as being dominated by Super Stellar Clusters (Age >= 10 Myr and Mass >= 10^5 Msun).The NIR colours of four SCCs in one of the galaxies suggest that these contain a larger amount of RSG stars than what the SSP models predict. The mismatch between observations and models however cannot be attributed alone to a mistreat of the RSG phase and needs to be further investigated.

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Resolving the extended stellar halos of nearby galaxies: the future of Near-Field Cosmology

The widely accepted Lambda Cold Dark Matter paradigm faces important challenges at the scales of individual galaxies, primarily linked to the implementation of baryonic physics in cosmological simulations. The study of resolved stellar populations in the nearest galaxies, or "near-field cosmology", provides key constraints on the physics underlying galaxy formation and evolution. In this talk, I will present the ongoing Panoramic Imaging Survey of Centaurus and Sculptor and the Magellanic Analog Dwarf Companions And Stellar Halos survey, targeting galaxies in the Local Volume within a range of masses and environments. The unique strength of such surveys is the exquisite synergy between wide-field, ground-based imaging and their extensive follow-up campaigns (HST, Keck, VLT, Magellan, AAT). Such surveys constitute the first accurate characterization of the past and ongoing accretion processes shaping the halos of these nearby galaxies and their satellite populations: they do not only quantitatively inform theoretical models of galaxy formation and evolution, but also represent a necessary testbed in preparation for the next generation of ground-based (LSST, GMT, TMT) and space-borne telescopes (JWST, WFIRST).

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Seminarios doctorantes

Galaxy mergers in a cosmological context

The latest hydrodynamic cosmological simulations (e.g., EAGLE, Illustris, IllustrisTNG) have been able to produce reasonably realistic populations of galaxies by tracking the evolution of dark matter, gas, stars, and black holes over a cosmological volume "representative" of the large-scale density field. However, such increasingly sophisticated cosmological simulations require equally sophisticated analysis tools. In this talk, I will first discuss how to connect galaxies in large cosmological simulations across cosmic time, which results in data structures known as merger trees. Then I will examine three essential and increasingly complex applications of the merger trees: (1) measuring the merger rate of galaxies, (2) finding out how galaxies acquire their stellar mass, and (3) investigating the impact of mergers on galaxy morphology.

Inefficient jet-induced star formation in Centaurus A

Star formation is one of the key mechanisms driving the formation and the evolution of galaxies across cosmic times. The physical properties and dynamics of the molecular gas influence the star formation efficiency, and therefore play a role in the growth of galaxies. Looking at large scales is therefore essential to understand the multi-scale physics of star formation. The environment may play a role in star formation. In particular, recent studies suggest that AGN can regulate the gas accretion and thus slow down star formation (negative feedback). However, evidence of AGN positive feedback is also invoked in a few radio galaxies (eg. Centaurus A, Minkowski's Object). I will present different studies of the northern filaments of Centaurus A at different resolutions. These filaments extend on scales up to 15 kpc, aligned with the radio-jet, and show evidence of recent star formation (Rejkuba et al. 2001). Along the radio jet, at the intersection of the radio jet and a HI shell (Schiminovich et al. 1994), CO emission has been detected with SEST in the shell (Charmandaris et al. 2000). We detect CO in a much larger area along the filaments with APEX, including outside the HI gas (Salomé Q et al. 2016a). Recently, we obtained ALMA observations along the filaments, at a resolution of ~20 pc (Salomé Q. et al. 2017). Such resolution enables to separate giant molecular without resolving them.

De los creadores de 'Gravity or Turbulence?', Cúmulos estelares. Formación, evolución temprana, y propiedades observacionales.

La gran mayoría de las estrellas se forman en cúmulos. En la presente charla presentaré resultados de simulaciones numéricas de núcleos densos masivos de nubes moleculares, mostrando: (a) cómo el colapso jerárquico y caótico de nubes masivas produce una pendiente en la función de masa inicial con pendiente de -1 de manera natural, hecho que sugiere fuertemente que la acreción es de tipo Bondi-Hoyle. (b) cómo las regiones con mayor curvatura producen que el material se apile, y los cúmulos masivos se forman a partir de la fusión de cúmulos más pequeños; (c) cómo la evolución del potencial tanto estelar como del gas es importante para la coalescencia de los cúmulos. (d) cómo el análisis de inestabilidad gravitacional, tanto de un core, como de un filamento., puede dar conclusiones erróneas sobre el estado dinámico de los cúmulos. Nuestros resultados son consistentes con una serie de características observacionales reportadas recientemente tanto en gas como en estrellas en cúmulos como el de la nebulosa de Orión.

The relation between globular cluster systems and supermassive black holes in spiral galaxies. The case study of NGC 4258

I give a summary of our project to explore the relationship between the total number of globular clusters, N_{GC}, and the mass of the central black hole, MBH, in spiral galaxies, and how it compares with that recently reported for elliptical galaxies. I present results for the globular cluster system of the Sbc galaxy NGC4258, from u*, g', i', r', and Ks data obtained with the Canada France Hawaii Telescope (CFHT). Thanks to water masers in a circumnuclear disk, the absolute distance to NGC 4258 has been derived directly by geometric means, and hence it has the most precisely measured extragalactic distance and supermassive black hole mass to date. The globular cluster (GC) candidate selection is based on the (u* - i') vs. (i'-Ks) diagram, which is a superb tool to distinguish GCs from foreground stars, background galaxies, and young stellar clusters, and hence can provide the best number counts of GCs from photometry alone, virtually free of contamination, even if the galaxy is not completely edge-on. We have thus increased to 6 the sample of spiral galaxies with measurements for both MBH and N_GC. NGC4258 has a specific frequency S_N=0.4±0.1 (random uncertainty), and it is consistent within 2 sigma with the N_GC vs. MBH correlation followed by elliptical galaxies. The Milky Way continues to be the only spiral that deviates significantly from the relation. Future work includes spectroscopic confirmation of cluster membership and hence validation of our method, and the study of the N_GC vs. MBH correlation in the remaining 8 northern spirals within 16 Mpc that have precise measurements of their BH masses, and for which we should finish collecting the required CFHT data in the coming months.

Hamburguers and burritos: 3D radiative transfer modelling of ALMA observations of young stellar objects.

I will present the tools developed by my student Andres Izquierdo to plug-in a variety of 3D analytical models to the radiative transfer code LIME. Then I will show our work in progress in the first two applications of these tools: 1) modelling ALMA observations of the massive YSO(s) in W33A, an object that we naively thought it was a massive disk in the pre-ALMA days, and that current data revealed is a multiple, complex system being fed by accretion filaments (burritos), 2) modelling of the effects of self-obscuration in the submillimeter appearance of class 0 disks, where we find that we can explain shallow (sub)mm spectral indices without the need to invoke grain growth, and reproduce recent resolved images of dark lanes (hamburguers) in class 0 YSOs when observed with the ~20 mas resolution provided by ALMA long-baseline observations.

From velocity dispersion to the dispersion of Astronomy

I will present a short summary of the work I did during my PhD on velocity dispersions of molecular gas in nearby galaxies. Despite the fact that molecular gas in galaxies is the most essential ingredient for the star formation process, its thorough characterization has not yet been accomplished. On 0.5 kpc scales (the average spatial resolution of my work), the measured CO velocity dispersions have a mean value of ∼ 12 km/s. These values are higher than previously expected, and are comparable to those measured for neutral atomic gas. To investigate the origin of these large dispersions, a comparison between interferometric and single-dish line width measurements for NGC 4736 and NGC 5055 (at ∼ 0.5 kpc resolution) and for the neighboring Andromeda galaxy, M 31, (at ∼ 100 pc resolution) is presented. At the end I will shortly speak about future projects for outreach in Astronomy.

The Gould’s Belt Distances Survey (GOBELINS)

I will present the results of an radio-astrometric VLBI program (GOBELINS) aimed at measuring the trigonometric parallaxes of tens on young stars distributed over the nearest star-forming regions (Taurus, Ophiuchus, Perseus, Orion, and Serpens). These observations provide the distances to these YSOs to an accuracy of about one percent that surpasses previous (mostly indirect) determinations by one order of magnitude. Aside from improving our knowledge about the distribution of local star-forming regions, these results reveal (for the first time) the 3D structure of individual regions. For instance, Taurus is found to be about 30 pc deep, with different clouds/filaments located at different distances.

Statistical Modelling of Solar Flare Extremes

Extreme value theory (EVT) is a unique statistical discipline that offers techniques and models for describing the unusual rather than the usual. By definition, extreme values are scarce, meaning that estimates are often required for outcomes that are much greater than have already been observed. Extreme value theory provides a class of models to enable such extrapolation based upon asymptotic analysis of probability distributions. In this talk I will introduce you to the methodologies of EVT and will take you through the models used by the theory. I will discuss its advantages and disadvantages and conclude the talk by giving a demonstration of an application of the EVT to extreme solar flare events.

The dynamics of a kinetic gas cloud in the vicinity of a black hole

Black holes are among the most spectacular predictions of Einstein’s theory of general relativity, and nowadays they lie at the forefront of theoretical physics and astronomy. In this talk, after providing a summary of the most important and intriguing properties of black holes, I will discuss recent work on the behavior of a collisionless kinetic gas under the influence of the gravitational potential of a Kerr black hole. Two regimes will be discussed. The first regime considers the case where the individual gas particles move on unbounded trajectories in which case the collection of particles describes an accretion process. The relevant parameters, such as the accretion and compression rates, are determined and the results are contrasted with those of the typical Bondi-Michel accretion model in the hydrodynamic case. The second regime focuses on the case where the gas particles are trapped in the gravitational potential and move on bounded trajectories. In this case, an interesting mixing phenomena seems to be taking place, which implies that although collisions between the gas particles are neglected in our model, the gas configuration settles down to a stationary, axisymmetric disk surrounding the black hole. This investigation which is performed in collaboration with my PhD student Paola Rioseco is partially motivated from the need of a thorough understanding for the behavior of matter in the vicinity of a supermassive black hole, such as Sagittarius A*, in view of upcoming observations of their shadows.

The fossil record method to reconstruct the evolution of galaxies

We want to explore what are the advantages and limitations of the fossil record method and show some results of the application of this technique using the MaNGA data. In the first part of this talk, we have post-processed two Milky Way-sized zoom-in Hydro simulations to create a set of mock observations to test the robustness of the fossil record inferences. In the second part, we explore the resolved star formation histories of 140 AGNs, 1,079 star-forming galaxies, 593 green valley galaxies and 961 quenched galaxies with the aim to reconstruct their evolutionary tracks along the main sequence diagram.

Molecular Cloud evolution: effects of magnetic fields and stellar feedback

I will present radiation-magnetohydrodynamic simulations aimed at studying the evolution of molecular clouds (MCs) formed by diffuse converging flows in the presence of magnetic fields and massive-star ionization feedback. I will discuss how the magnetic field tends to enhance the star-formation activity by suppressing the dynamical instabilities that produce turbulence within MCs. This is an important but counterintuitive result since the common belief is that the magnetic field provide support to molecular clouds against its self-gravity, regulating thus the process of star formation. Finally, I will discuss the impact of supernova explosions and UV feedback in the final stages of the cloud evolution. Particularly, I will discuss the structure and expansion laws of HII regions in our highly structured MCs as well as the implications of our results for theoretical models.

Runaways and weathervanes: the shapes of stellar bow shocks

Stellar bow shocks are the result of the supersonic interaction between a stellar wind and its environment. Some of these are "runaways": high-velocity stars that have been ejected from a star cluster. Others are "weather vanes", where it is the local interstellar medium itself that is moving, perhaps as the result of a champagne flow of ionized gas from a nearby H II region. We propose a new two-dimensional classification scheme for bow shapes, which is based on dimensionless geometric ratios that can be estimated from observational images. The two ratios are related to the flatness of the bow's apex, which we term planitude and the openness of its wings, which we term alatude. We calculate the inclination-dependent tracks on the planitude-alatude plane that are predicted by simple models for the bow shock shape. We also measure the shapes of bow shocks from three different observational datasets: mid-infrared arcs around hot main-sequence stars, far-infrared arcs around luminous cool stars, and emission-line arcs around proplyds and other young stars in the Orion Nebula. Clear differences are found between the different datasets in their distributions on the planitude-alatude plane, which can be used to constrain the physics of the bow shock interaction and emission mechanisms in the different classes of object.

VLTI - GRAVITY chromatic imaging of Eta Car's core

Eta Car is one of the most massive, and intriguing, Luminous Blue Variables known. In its core resides a binary with a 5.54 years orbital period. Visible, infrared, and X-ray observations suggest that the primary star exhibits a very dense wind with a terminal velocity of about 400 km/s, while the secondary shows a much faster and less dense wind with a terminal velocity of 3000 km/s. The wind-wind collision zone at the core of Eta Car is thus a complex region that deserves a detailed study to understand the effect of the binary interaction in the evolution of the system. In this talk we will perform a review of the basic principles of the optical/near-infrared interferometry, together with our unique imaging campaign with VLTI - GRAVITY of the Eta Car's core. The superb quality of our interferometric data, together with state-of-the-art image reconstruction techniques, allowed us to obtain, with milliarcsecond resolution, continuum and chromatic images across the BrG and HeI lines in the Eta Car K-band spectrum (R~4000). These new data together with models of the primary wind of Eta Car has letting us to characterize the spatial distribution of the dust and gas in the inner 40 AU wind-wind collision zone of the target.

Radio-astrometry to Young Stars in the Gaia era

Dust in star forming region efficiently absorb the optical emission from stars inside them and, thus, many Young Stellar Objects will not be detected and studied by the Gaia satellite. Fortunately, these stars are often associated with radio emission, which may be used for astrometric studies. In this talk I will present recent results in this context. First, we have used archived Very Large Array (VLA) observations, spanned during the last 30 years, to measure the proper motion of ~100 YSOs in the ONC core, which gave us an interesting view of the stellar kinematics of this region and select stars with peculiar proper motions. However, the angular resolution of the VLA is much smaller than that provided by the Gaia telescope, but this is not the case of the Very Long Baseline Array (VLBA). VLBA has been used during the last decade to determine distances to several near and far galactic star forming regions with precisions comparable and, in some cases, better than those that the Gaia satellite will provide. In the second part of my talk, I will focus on recent results of distance measurements, using observation with the VLBA, to nearby (<1 kpc) star forming regions: Monoceros R2, LkH\alpha 101 and IRAS 16293-2422 (in Ophiuchus).

Multiple stellar generations in Galactic Globular Clusters.

By adopting the empirical estimates of the Helium enhancement (delta Y) between consecutive stellar generations in a sample Galactic Globular Clusters, as well as the present mass ratio between consequtive stellar generations (M(j-1)G=M(j)G) and the present total mass of Galactic Globular Clusters (MGC), we uniquely constraint the star formation efficiency (epsilon) of each stellar generation in these stellar systems. In our approach, the star formation efficiency is the central factor that links the stellar generations as it defines both the mass in stars in each generation and the remaining mass available for further star formation, fixing also the amount of matter required to contaminate the next stellar generation. In this way, epsilon is here shown to be fully defined by the He enhancement between successive generations in a GC. Our approach allows also for the evolution of clusters and thus considers the possible loss of stars through evaporation or tidal interactions. We also show that globular clusters fit well within a deltaY vs M(j-1)G/M(j)G diagram which indicates three different evolutionary paths. The central one is for clusters that have not loss stars, through evaporation or tidal interactions, from either of their stellar generations, and thus their present MGC value is identical to the total amount of low mass stars (M < = 1 Msol) that resulted from each stellar generation. Other possible evolutions imply either the loss of first generation stars or the combination of a low star formation efficiency in secondary stellar generations and/or the loss of stars from the next generation. From these considerations we derive a lower limit to the mass (Mtot) of the individual primordial clouds that gave origin to each of the globular clusters in our sample.

A direct primitive variable recovery scheme for hyperbolic conservative equations and some applications to relativistic hydrodynamics.

In this talk I will discuss a Primitive Variable Recovery Scheme (PVRS) to solve any system of coupled differential conservative equations. This method obtains directly the primitive variables applying the chain rule to the time term of the conservative equations. With this, a traditional finite volume method for the flux is applied in order avoid violation of both, the entropy and "Rankine-Hugoniot" jump conditions. The time evolution is then computed using a forward finite difference scheme. This numerical technique evades the recovery of the primitive vector by solving an algebraic system of equations as it is often used and so, it generalises standard techniques to solve these kind of coupled systems. Applications to special relativistic hydrodynamics including in some cases a fixed background curved space-time will be discussed. I will also talk about the development of aztekas.org a free GPL'd code for solving any set of coupled conservative equations.

Latest results from the HAWC Observatory

The High Altitude Water Cherenkov Observatory (HAWC) is a facility designed to detect extensive air showers produced by very-high-energy gamma rays and cosmic rays interacting with our atmosphere. It is located in the Pico de Orizaba National Park in Puebla, México. Since its inauguration in April 2005, the HAWC observatory has been operating almost continuously detecting gamma rays coming from galactic and extragalactic sources. In this talk an overview of the most relevant scientific results from the HAWC Collaboration will be given.

The Onset of Ionization Feedback in High-Mass Protostars

Using the VLA to reach sensitivities of 3–10 μJy/beam, we found that radio continuum sources are more commonly found towards high-mass protostars than previously expected. Many of these radio continuum sources are weak (on the order of < 1 mJy) and have morphologies and other observational parameters that resemble collimated ionized jets, which is in general agreement with recent theoretical models developed exclusively for high-mass protostars based on core accretion. We are building a sample of ~20 high-mass protostars with comprehensive observations from radio to mid-IR using VLA, SOFIA and ancillary data to test and refine these new protostar formation models that predict both the morphology and spectral energy distribution. I will present results showing that extending the infrared SEDs to radio wavelengths is effective in breaking degeneracies in the fitted model parameters.

An introduction to... me: N-body, dwarf galaxies and Dark Matter

Dwarf spheroidal galaxies are dark matter dominated. Therefore, they are ideal to test any dark matter model. In this colloquium I will talk about my previous work on stellar substructures in dwarf spheroidal galaxies and how important they are to constrain dark matter models. I will continue to present our newly discovered stellar substructures in Sextans, Carina, Leo I and Leo II. Finally, I will present my current and future work.

Probing Young Planets in Protoplanetary Disks: Theory Confronts Observations

Recently commissioned telescopes and instruments (e.g., Subaru, GPI, VLA, ALMA, EVLA) are now finally able to resolve the protoplanetary disk down to the AU scale, and a rich variety of disk features have been revealed: gaps, large scale disk asymmetry, and spiral arms. To confront these observations, theoretical models need to be developed so that we can use observations to constrain the physics of disk structure and planet formation. In the talk, I will summarize our recent progress on planet-disk interaction study, focusing on explaining the observed spirals and how a single planet can lead to multiple gaps. To directly find young planets, I will argue that disks around these forming planets, so-called circumplanetary disks, could be the key and we may have already found some circumplanetary disk candidates.

A view of the maternities of massive stars with ALMA

High-mass stars are known to be formed within massive and dense clumps with masses of typically 1e3 Msol and sizes of 1 pc . However, the way in which the high-mass are formed is still an open question. Here we discuss ALMA observations of a handful of massive and dense clumps in early stages of evolution, previous to the formation of high-mass stars, revealing the spatial distribution and kinematics of the small scale structures, or cores, within the clumps. We find that the Core Mass Function is strikingly different from that of the IMF.

The submm to cm view of protoplanetary disks: dust growth and ionized gas

Planetary systems have long been known to form from the gas and dust of circumstellar disks. In recent years, the transformational observations provided by ALMA have increased and shaped our understanding of these systems. However, the study of several important physical processes, such as dust growth or gas photoionization and dispersal, requires observations across a wider range of wavelengths than what ALMA can probe. In this talk I will show the combined results of VLA and ALMA observations toward two protoplanetary disks that show signs of ongoing planetary formation: GM Aur and HD 169142. In both disks, the ALMA and VLA observations revealed the presence of multiple rings and gaps, likely produced by the dynamical interaction between the disks and young planets in them. At the same time, both sources show substantial free-free emission associated with ionized gas. In the case of GM Aur, we resolve this emission and see that it is associated with a radio jet and a photoionized disk, providing new insights into disk photoevaporation and dispersal.

The Interplanetary Scintillation (IPS) Technique to Study Solar-Wind Properties Throughout the Inner Heliosphere

Interplanetary scintillation (IPS) manifests itself as a variation in the radio signal received from a distant, compact radio source on the sky as the radio waves traverse the interplanetary medium due to density inhomogeneities in the outflowing plasma. IPS allows us to infer the speed and density of the plasma. There are two types of techniques that provide IPS solar wind speed determinations in the heliosphere: Single-Station analysis (SSA) and multi-station Cross Correlation Function (CCF) analysis. In order to combine and complement solar wind speed observations, it is important to validate results and methodologies of the two techniques. We apply the SSA to previously-well studied European Incoherent SCATter (EISCAT) and Multi-Element Radio-Linked Interferometer Network (MERLIN) observations of IPS with well-known results using the CCF methodology in order to know the capabilities of the SSA to describe complex events and seeks to obtain improved parameter fits using the SSA of individual IPS spectra.

Scaling relation in AGN: the importance of obscuration in the X-ray variability plane

Scaling relations are the most powerful astrophysical tools to set constraints to the physical mechanisms of astronomical sources and to infer properties for objects where they cannot be accessed directly. We re-investigated one of these scaling relations using mostly NLSy1 and Sy1 (González-Martin 2018); the so-called X-ray variability plane (or mass-luminosity-timescale relation, McHardy et al. 2006). This relation links the power-spectral density (PSD) break frequency with the SMBH mass and the bolometric luminosity. We used all available XMM-Newton observations of a sample of 22 Sy1 and NLSy1 to study the PSD and spectra in short segments within each observation. This allows us to report for the first time that the PSD break frequency varies for each object, showing variations in 19 out of the 22 AGN analyzed. Our analysis of the variability plane confirms the relation between the break frequency and the SMBH mass and finds that the obscuration along the line of sight (or the variations on the obscuration using its standard deviation) is also a required parameter. The X-ray variability plane found by McHardy et al. (2006) is roughly recovered only when we use unobscured segments. We speculate then that the PSD shape is related with outflowing winds close to the accretion disk.

Planet formation observed at millimeter and IR wavelengths

Observations at millimeter wavelengths and in IR scattered light have revealed numerous substructures in protoplanetary disks when observed at high spatial resolution. These substructures are of primordial importance as they might stop the dust radial migration onto the stars and concentrate efficiently dust particles, then yielding to the formation of planetary embryos. In this talk, I will present recent ALMA observations of two planetary disks around the Herbig stars HD 142527 and MWC 758. These disks are well-known for showing numerous outstanding features. They present dust asymmetries, with a small gas-to-dust ratio, that are thought to be ideal places to develop hydrodynamical instabilities (such as the streaming instability) yielding afterwards to gravitational collapse and planetary embryos formation. Additionally, the disks feature spirals observed with ALMA and previously detected with Subaru and the instrument Sphere of the VLT that might trace planets already formed. Planets with a mass larger than about 1 Jupiter mass are known to produce cavities and spirals in protoplanetary disks, that might be more visible than the planets themselves. However, other scenarios including perturbations by a stellar encounter, shadows cast by the inner regions of the disks, among others, will also be discussed.

The inner MIR emission of local QSOs

Active galactic nuclei (AGN) are among the most exciting objects in the universe due to the large energy range covered by their spectrum from radio to gamma rays, which can be explained trough several physical components and processes. With the advent of large ground based telescopes like the 10.4m Gran Telescopio CANARIAS (GTM) and the mid-infrared camera CANARICAM, a better understanding of the nuclear dust in AGNs have been reached. In this talk I am going to present the results that we obtained from studying the mid-infrared emission in high luminosity AGNs. Additionally, I going to show some results of our progress work on the study of the silicate features in type 1 AGNs and our looking for optical obscured AGNs.

Spirals, rings and arcs (around evolved stars)

The Hubble (HST) and Spitzer telescopes were the first instruments to unveil the presence of rings and arcs around evolved low-mass stars (AGB stars, proto-PNe and PNe)in great detail. Since the mid-2000s it was suggested that these structures were ubiquitousaround evolved low-mass stars. We searched the complete archive of the HST and Spitzer to characterise these structures, study their physical properties and characterise their formationmechanisms. In this talk we present the observational results of our survey, the predictions of simple radiation-hydrodynamic simulations as well as the future of the project.

Droplets: Pressure-Dominated Sub-0.1 pc Coherent Structures in L1688 and B18

In this talk, I will present an analysis of newly discovered coherent structures in the L1688 region of Ophiuchus and the B18 region of Taurus. The structures are identified in a search of ammonia spectral cubes from the Green Bank Ammonia Survey (GAS; Friesen et al. 2017) alongside Herschel maps of thermal dust emission, looking for regions of high density and near-constant, almost-thermal, velocity dispersion. Eighteen coherent structures are revealed, twelve in L1688 and six in B18, each of which shows a sharp “transition to coherence” in velocity dispersion around its periphery. We call these structures “droplets,” owing to their small sizes and masses, as well as their gravitational unboundedness. To examine the droplets’ kinematics and internal structures, I will present a virial analysis and comparisons to a Bonnor-Ebert sphere, a logotrope, and previously observed starless cores. Lastly, by comparing to MHD simulations, I will investigate several potential formation mechanisms for droplets, and speculate on the role that droplets, and coherent structures more generally, may play in the process of star formation.

Independent Cosmological Constraints from HII Galaxies

We use HII galaxies in a joint likelihood analysis with other complementary cosmic probes (Cosmic Microwave Background, Baryon Acoustic Oscillations) to trace the Hubble relation through most of cosmic history and thus obtain constraints for the Hubble constant and the parameter space of the Equation of State of Dark Energy, the putative causal agent behind the accelerated expansion of the Universe, which is today a most intriguing problem in physics. The cosmological constraints thus obtained, are in excellent agreement with those of a similar joint analysis using the well established Type Ia Supernovae Hubble expansion probe.

Testing barred galaxy models

About 30% of disc galaxies in the local Universe present prominent stellar bars in their centers. This fraction of barred galaxies depends strongly on several physical properties of the galaxies, such as stellar mass, colour and overall morphology. In this talk I will give a short review of the role of the dark matter halo, the galactic spin and the gas content in the formation and evolution of stellar bars as predicted by theoretical studies, and I will provide observational results that can help to discriminate between different theoretical models.

The planetary nebula HuBi 1, Rebel with a Cause

Planetary nebulae, the descendants of low- and intermediate-mass stars, have characteristic onion-like ionization structure, with the highest ionization species closer to the central star. This is true for all planetary nebulae, but HuBi 1, which shows an inverted ionization inner shell. There is a reason for this oddity, the peculiar evolutionary path of its central star, which makes HuBi 1 the missing link of the population of cool C-rich central stars of planetary nebulae and explains many of their properties.

Extreme quasars at high redshift

The study of the AGN accreting close to the Eddington limit (L/LEdd~1) has taken an important role, due to their potential use as standard candles for cosmological applications. With the purpose to understand the physics of extreme quasar, we perform a spectroscopic analysis of a sample of highly accreting quasars at high redshift (z~2–3). Our sample were observed with the OSIRIS spectrograph on the GTC 10.4 m telescope located at the Observatorio del Roque de los Muchachos in La Palma. The highly accreting quasars were identified using the 4D Eigenvector 1 formalism, which is able to organize type 1 quasars over a broad range of redshift and luminosity. The kinematic and physical properties of the broad line region have been derived by fitting the profiles of strong UV emission lines such as AlIII λ1860, SiIII]λ1892 and CIII]λ1909. We find that AlIIIλ1860 can be associated with a low-ionization virialized sub-system. xA sources show strong blueshifts in the high-ionization lines like in CIVλ1549, indicating a relation between the high Eddington ratios and the productions of outflows. The extreme radiative properties of highly accreting quasar make them prime candidates for maximum feedback effects on the host galaxy. The characterization of extreme quasar allow to assemble large samples of extreme quasars from the latest data releases of the SDSS, especially useful for deriving independent estimates of ΩM in the redshift range 1

Reducing spectral analysis time: Mega-database of CMFGEN models and FITspec for automatic fit of O type stars

In a collaboration of the ABACUS-CINVESTAV laboratory, the ESFM, the ININ and the Universidad Iberoamericana we have developed a database of stellar atmospheric models with the code CMFGEN (Hillier and Miller, 1998). The models were calculated in the cluster ABACUS of the ABACUS-CINVESTAV Applied Mathematics and High Performance Computing Laboratory and cover the region of massive main sequence stars. Currently the database has 40,000 models, our goal is to reach 75,000 models. Our research group has developed software tools for the administration of the database, queries under a search criteria, visualization of several spectra simultaneously and automatic adjustment of models. One of these tools is the FITspec program (Fierro et al. 2018), which performs a quantitative spectroscopic analysis based on the equivalent widths of He I, He II, and Balmer lines, reducing the time needed for the spectral analysis from months to hours, optimizing in this way the calculations. In addition to the description of the database, I will present partial results of the analysis of a sample of type O stars from the spectroscopic catalog of San Pedro Mártir.

Emisión no térmica y aceleración de partículas en jets protoestelares

Resolved star formation and stellar feedback in galaxies

Standard cosmological models over predicts the number of small galaxies. Thus, a self-regulation of the star formation is commonly accepted, although is far from being observed and understood. Star formation and its self-regulation is a key process which the models oversimplify because of their limited resolution. If we want to understand the self-regulation of star formation, we need to study the resolved laws of star formation. I will present the results of the resolved main sequence of star formation on star forming clumps from a sample of 46 pair of galaxies, and 38 non interacting spirals. We found that the resolved main sequence of star formation is broken on kpc scales because the star formation is more centrally concentrated than the stellar mass. We also found that the clumps in the interacting galaxies have more SFR per stellar mass compared to the non interacting spirals. I will also present preliminary results on the analysis of the stellar populations of NGC 628 using MUSE data, and the code SINOPSIS. We compared the SFRs at the two most recent ages bins in different regions. I will show how we are able to characterize the self-regulation of the star formation between these two ages.

Teorías de mundos brana: Desde la Astrofísica hasta la Cosmología

En esta charla discutiremos los efectos de proponer una dimensión extra más, realizando cambios a la Relatividad General estándar. En particular, discutiremos los modelos de dimensiones extra conocidos como de Randall-Sundrum (mundos brana), en los cuales sus configuraciones son apropiadas con la finalidad de tener comportamientos estándares a bajas energías. La charla está diseñada para discutir las razones por las cuales fueron motivados los mundos branas y sus consecuencias en la astrofísica y cosmología moderna; proponiendo constricciones de sus parámetros libres y su viabilidad como posibles alternativas a la gravitación Einsteniana.

Feedback from Massive Stars

Massive stars impact their surroundings through strong winds, intense radiation fields, outbursts and supernova explosions. Their compact remnants are sources of X-rays and Cosmic Rays, which penetrate deep into molecular clouds affecting both temperature and chemistry. Ionizing radiation is a key feedback process for young stars, so I will first discuss the ionization-front instability to determine if and when it could produce pillars and globules in expanding HII regions. Then I will show results from some work we are doing on the stellar-wind bubble NGC 7635 and its X-ray and infrared emission. Finally I will show results from studying the time-dependent chemistry of molecular clouds when exposed to intense X-ray flares. Even a 10 or 20-year X-ray flare can change the chemistry of a cloud for thousands of years afterwards. We find that CO is destroyed much more rapidly than H2, providing a possible explanation for some of the CO-dark clouds that are found in extreme environments.

How do evolved stars lose mass?

In old stellar systems, most of the matter returned to the ISM comes from AGB stars. We don't know exactly how it happens, because many different phenomena occur at the same time. Here, I will present recent observations we have taken of stellar winds. I hope to convince you that it is stellar pulsations that dictate mass loss from stars, while radiation pressure dictates how fast material leaves the star. In the process, I will touch on topics ranging from interstellar radiation to the evolution of planetary systems, and I will note the impact these results have on stellar evolution theory and modelling of stellar populations.

Polarización de las Galaxias Activas y otros astros

El campo magnético de las galaxias de núcleo activo (AGN) juega un papel relevante en la regulación de la acreción de material al agujero negro y en la retroalimentación al medio intergaláctico en forma de chorros y/o vientos.Observaciones polarimétricas en el cercano infrarrojo abren una ventana para investigar el campo magnético de las regiones centrales de las AGN. Sin embargo, existen apenas un puñado de trabajos que exploran la polarización central de las AGN y, por lo tanto, la física de la región central es menos conocida.En esta charla presentaré cómo el análisis del espectro polarizado de una muestra de AGN permite desentrañar el mecanismo polarizante. Este estudio arroja información nueva sobre los campos magnéticos y la física de los AGN. Finalmente, mostraré algunos ejemplos de cómo observaciones polarimétricas pueden profundizar el estudio de otros astros.

Dust Production from Evolved Stars in the Local Group

Infrared observations of nearby galaxies and the Milky Way show that there are two main sources of ISM dust: the winds of evolved stars and supernovae ejecta. However, the total dust contribution from evolved stars relative to supernovae, and how it changes with metallicity, is less certain. Infrared photometric and spectroscopic Spitzer Surveys of the Large and Small Magellanic Clouds (LMC, SMC): Surveying the Agents of Galaxy Evolution (SAGE) resulted in the discovery of thousands of evolved stars. Here, I will describe how the composition and quantity of dust produced by these stars depends on metallicity. I will also discuss how the mid-IR stellar populations of the Magellanic Clouds can be used as a template for potential observations with JWST, and how we have applied this to our observing programs of stellar populations Local Group galaxies and SN1987A with JWST.

Numerical modeling of the 1840s major eruption of Eta Carinae

In this talk, I will present theoretical results from both analytical and numerical models of the 1840s eruption of the massive star Eta Car, that resulted in the formation of a bipolar structure which is commonly known as the large "Homunculus nebula". During this event, the star expelled into the circumstellar material a total mass of ~10 Msol and released a total energy of E~ 10^(50) ergs over a very short time (< 5 yr). In the case of Eta Car, a brief explosion scenario provides a potential explanation for the behavior of the historical light curve of Eta Car a few years after the nineteenth century outburst, as well as some observed physycal properties of the nebula. Nonetheless, I show through numerical simulations that an explosion model for the 1840s major eruption of Eta Car is not able to account for the estimated age of the large Homunculus.

An inventory of the stellar sources of dust in the Universe

Dust is a key ingredient in many astrophysical processes. It is the catalyst for the formation of molecular hydrogen, and allows efficient cooling of collapsing cores leading to the formation of stars. Information about the astrophysical processes responsible for its growth and formation is imprinted in the dust in the form of mineralogy. Unlike gas, therefore, dust retains a memory of these processes for timescales up to ~1 Gyr.Dust is formed in the outflows of low-mass (1-8 Msun) evolved stars and also in the explosions of massive (>8 Msun) evolved stars. However, supernovae (SNe) reverse shocks also destroy significant amounts of dust. While the net contribution of dust from SNe is therefore highly uncertain, it is relatively easy to determine the total input from asymptotic giant branch (AGB) stars, which are numerous in present-day star-forming galaxies. Our group has identified AGB candidates in many nearby galaxies, and has used a grid of radiative transfer models to fit their spectral energy distributions in order to derive the total dust input to the interstellar medium (ISM). In this talk, I will summarise our findings and also advertise ongoing modelling and observational efforts related to dust in various environments as well as AGB stars in the Solar Neighbourhood.

Numerical Studies of Jet Formation in the Solar Atmosphere using the Newtonian CAFE MHD code

Using the Newtonian CAFE MHD code to perform numerical resistive 2-3D MHD simulations, we have shown that jets with features of Type II spicules and cool coronal jets can be formed due to magnetic reconnection. To perform 2D simulations, as initial models we used two different magnetic configurations (i) a symmetric case, i.e. when the magnetic field strength of the two neighboring magnetic loops is equal and (ii) an asymmetric case when magnetic strength of loops is different. In the case (i), the excited jets rise vertically, whereas in the case of an asymmetric configuration (ii) the jet shows an inclination, which depends on the magnetic field strength ratio of the two loops and the distance between them. In the 3D simulation the magnetic configuration corresponds to a 3D potential magnetic field extrapolated from a dynamic realistic MHD simulation of solar photospheric magnetoconvection, which is mimicking quiet-Sun. We have found that the formation of the jet depends on the Lorentz force, which helps to accelerate the plasma upward. Analyzing various properties of the jet dynamics, we found that the structure shows Doppler shift, rotational and torsional motions. The morphology, the upward velocity coveting a range up to 130 km/s, and the timescale formation of the structure between 60 and 90 s, are similar to those expected for Type II spicules.

A toy model for the evolution and quenching of galaxies after z~3

I will discuss a toy power-law model for the growth of black holes ingalaxies and their role in quenching. Galaxies while star-forming areassumed to exist at the centers of relatively undisturbed dark halos,and their stellar mass and radii are linked to halo properties viasimple relations. Central stellar density is assumed to correlatewith black hole mass. Quenching occurs when total energy emitted bythe black hole equals some total energy needed to heat the halo, whichis assumed to equal the gravitational binding energy of the halo gas. These assumptions matchthe observed distributions of star-forming and quenched galaxies in the R_e - M* and Sig_1 - M* planes from z ~ 3 to now. Animplication is that halos are a 2-parameter family that imprint theirproperties on the 2-D family of galaxies and that halos and the BH massesare connected through galaxy effective radii.

Astrometría ultraprecisa con interferometría de muy larga base en el centimétrico y milimétrico

The Very Long Baseline Interferometry (VLBI) technique combines radio telescopes separated by thousand of kilometers to achieve the highest spatial resolutions in all of astronomy. Motivated by the need of basic stellar parameters determinations such as distances, sizes, and masses, in the star-formation field, the first goal of this work was to obtain precise measurements of distances and proper motions of young stars in the Ophiuchus and the Serpens/Aquila regions by performing multi-epoch VLBI observations with the Very Long Baseline Array (VLBA). From our observation, we were able to further investigate the structure of the clouds, derive orbital parameters of binary systems and examine the relation between the properties of young stars, such as evolutionary stage and multiplicity, and their level of radio emission detectable on VLBI baselines. The second part of the thesis focused on the source Sgr A*, which is associated with the nearest supermassive black hole, at the Galactic Center. High angular resolutions, only attainable with VLBI at millimeter wavelengths, are needed in order to detect the smallest scales and investigate phenomena related to black hole accretion and jet launching. We initiated operations for mm-VLBI observations at the Large Millimeter Telescope and performed a 3.5-mm VLBI experiment in concert with the VLBA. Because at this short wavelength the effect of the atmosphere on interferometric visibilities becomes severe, we developed and used non-imaging methods to study the millimeter emission from Sgr A*. We determined the intrinsic shape and orientation of the source at individual epochs, and interpreted the detection of substructure in the source image as possibly introduced by the interstellar medium in the direction of the Galactic Center.

Observando el Universo a muy altas energías desde Tierra: MAGIC y HAWC

Los rayos gamma de muy alta energía (E > 100 GeV) no pueden penetrar la atmósfera de la Tierra y su detección directa en el espacio es técnicamente imposible, por lo que son necesarios detectores en tierra de gran tamaño. Los telescopios MAGIC y el observatorio HAWC son ejemplos contemporáneos de las dos principales técnicas de detección de rayos gamma de muy alta energía. En esta charla se presentará las principales diferencias entre estas técnicas con sus ventajas y desventajas además de mostrar algunos de los resultados más recientes.

Se hará un resumen de los servicios y tareas a cargo de cada uno de los miembros del personal de Cómputo del IRyA. Se especificará el protocolo para la interacción usuario-Cómputo esperada (tickets), el cual nos permite atender el mayor número de solicitudes posible dadas las limitaciones de personal y tiempo. Se mencionarán los mayores problemas que se han afrontado en el último año, así como lo que se ha hecho para intentar resolverlos.

The Fish that Turned into a Horse: revealing the Pisces/Pegasus kinematic association

I present evidence for the existence of a new young moving group (MG) in the Northern hemisphere -- the Pisces MG, based on optical spectroscopy and kinematic data from the Gaia TGAS catalog. Constituents of moving groups provide extremely useful tests of pre-main sequence evolution and are prime targets for direct imaging of exoplanets and circumstellar material. Whilst the majority of searches for nearby, young moving groups have focused on candidates in the Southern hemisphere, the Northern hemisphere remains relatively untapped. Motivated by the potential to find new young stars in the Northern hemisphere we compiled a list of several thousand short-period, X-ray active FGK stars (8

Demographics of molecular cloud life cycle and star cluster formation

New multi-line mapping surveys of molecular clouds (e.g., CHaMP, ThrUMMS), are enabling an unprecedented demographic analysis of the physics of entire cloud populations. Key insights from such surveys include (but are not limited to): (1) The existence of a vast population of sub-thermally excited, massive dense clumps, the majority of which are not engaged in vigorous star formation; (2) The pressure-stabilisation of these clumps against dispersal by their overlying envelopes, implying long (several ×10^7 yr) cloud lifetimes; (3) A new CO → H2 conversion law accounting for these numerous pc-scale, low-excitation, high-opacity and high column density clumps, suggesting the total molecular mass of clouds, from pc to kpc scales in the Milky Way, may be underestimated by a factor of 2–3, and increasing the gas depletion timescale by the same factor; (4) A revision to the concept of large molecular clouds, including GMCs, to be structures composed of pc-scale clumps (∼75% by mass) connected by a more diffuse, large-scale envelope (∼25% by mass); and (5) Evidence for widespread flows of molecular material, both onto and away from existing cloud structures, on timescales consistent with the long cloud lifetimes and the overall low star formation efficiency in the Milky Way. We summarise these results and discuss implications for our understanding of star formation and the life cycle of molecular clouds.

T.B.D.

Closing the gap between simulations and observations

In this talk I will give an overview over my latest results to compare current observations with latest 3D radiation MHD simulations of turbulent protoplanetary disks. I will focus on the dust thermal emission in protoplanetary disks, covering the outer regions which emit in the sub/mm and the inner regions which are expected to be thermally ionized and to emit in the near infrared. In the first part of my talk I will discuss the recent works by Flock et al. 2015 and Ruge et al. 2016 which are able to explain ring formation and dust concentration at the dead-zone outer edge. In these works we show that ALMA is able to resolve these structure in the dust continuum emission. In the second part of my talk I will focus on the results of first 3D radiation non-ideal MHD simulations including the inner dust rim of protoplanetary disk (Flock et al. 2016a, Flock et al. 2016b). The results show the detailed shape of the inner rim and they compare well with observational constraints. Synthetic images of the thermal dust emission in the near infrared are presented and compared with recent interferometry observations. Finally I will draw conclusions on the results and discuss about the possibility to observe MRI activity with current telescope facilities.

Análisis de Turbulencia en el survey SEDIGISM

En este trabajo mostramos los resultados preliminares sobre un estudio estadístico de la turbulencia en los datos del survey SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium). Los datos fueron tomados con el telecopio APEX. Para el estudio estadístico de turbulencia aplicamos la técnica VCA: Velocity Channel Analisys (Lazarian & Pogosyan 2000) sobre los cubos de datos de la linea 13CO(2-1) de 6 nubes moleculares extraídas con el algoritmo SCIME (Colombo et al. 2015). Los espectro de potencia de las nubes muestran comportamientos similares, lo cual propone una misma escala de inyeción de energía de turbulencia (1-10 pc). Estos resultados se encuentran publicados en Schuller et al. (2017). En esta charla discutiremos los compartamientos de estos espectros y su potencial para el análisis de turbulencia en el gas molecular del medio interstellar.

The GLOSTAR VLA survey

Massive stars dominate the galactic environments and the full picture on how they form has not been obtained yet. In fact, this is a hot topic in the modern astronomy. In the last few years large surveys have apported new clues and have dramatically changed our view on massive star formation. These blind surveys allow to study ALL evolutionary stages of massive star formation in an unbiased way. The GLObal view of STAR formation survey is an ambitious project that will observe the galactic plane by using interferometric VLBI, submm/FIR and VLA observations. In this talk I will focus on the Galactic plane VLA survey, where we observed simultaneously the continuum and, Methanol, Formaldehyde and Radio Recombination Lines. Also, I will talk about our recent results in the range l = 28degrees to 36degrees and the galactic center region.

Average galaxy Star formation histories, galaxy mergers and structural properties over the last 13.3Gyrs

This talk presents new determinations of the stellar-to-halo mass relation (SHMR) at z = 0 − 10 that match the evolution of the galaxy stellar mass function, the SFR − M relation, and the cosmic star formation rate. We utilize a compilation of 40 observational studies, corrected for potential biases. Using our robust determinations of halo mass assembly from the several cosmological N-body simulations and the SHMR, we infer star formation histories, merger rates, and structural properties for average galaxies. Our main findings: (1) The halo mass M50(z) above which 50% of galaxies are quenched coincides with sSFR/sMAR~1, where sSFR is the specific star formation rate and sMAR is the specific halo mass accretion rate. (2) M50 increases with redshift, presumably due to cold streams being more efficient at high redshift while virial shocks and AGN feedback become more relevant at lower redshifts. (3) The ratio sSFR/sMAR has a peak value, which occurs around Mvir ≈ 2 × 10^11Msun . (4) The stellar mass density within 1 kpc, Σ1, is a good indicator of the galactic global sSFR. (5) Galaxies are statistically quenched after they reach a maximum in Σ1, consistent with theoretical expectations of the gas compaction model; this maximum depends on redshift. (6) In-situ star formation is responsible for most galactic stellar mass growth, especially for lower-mass galaxies. (7) Galaxies grow inside out. The marked change in the slope of the size–mass relation when galaxies became quenched, from d log Reff /d log M 0.35 to 2.5, could be the result of dry minor mergers

Materia Oscura de Campo Escalar: consecuencias en la formación de estructura en el régimen lineal

En este trabajo se hablará sobre la materia oscura. Se dará una introducción donde se expondrán las evidencias de la existencia de materia oscura en el universo. Posteriormente, se introducirá el modelo teórico de materia oscura fría, así como también un candidato a materia oscura conocido en la literatura como partícula tipo axion, basado en un campo escalar con un potencial trigonométrico. Se expondrá cómo este modelo de campo escalar reproduce observables cosmológicas como las anisotropías del fondo cósmico de radiación y el espectro de potencia de materia. En particular se quiere elucidar si el potencial característico de partículas tipo axion juega algún papel crucial en la formación de estructuras a gran escala en el régimen lineal

Studying compact radio sources associated with UCHII regions

Ultra-Compact (UC)HII regions represent a very early stage of massive star formation whose structure and evolution are not yet fully understood. Interferometric observations in recent years show that some UCHII regions have associated compact sources of uncertain nature. Based on this, we started a high-resolution VLA observational campaign at several of selected UCHII regions in order to report additional cases of compact sources embedded in UCHII regions. As a preliminar result, we find 13 compact sources associated to 9 UCHII regions. Although unveiling the nature for the newly detected sources is a work in progress, we assess some of their observational properties. According to the results, we can distinguish between two classes of compact sources. One class corresponds to sources that probably are deeply embedded in the dense ionized gas of the UCHII region. These sources are being photo-evaporated by the exciting star of the region. They may play a crucial role in the evolution of the UCHII region as the photo-evaporated material could replenish for 10^4 − 10^5 yr the expanding plasma and might provide a solution to the so-called 'lifetime' problem for these regions. The other class of compact sources is not associated with the densest ionized gas of the region. Most of these sources appear unresolved and their properties are varied. We speculate on the similarity between these sources and those of the Orion population of radio sources.

Simulations of FIR line emission from galaxies at high redshift

The interstellar medium (ISM) plays an important role in the evolution of galaxies, and the best way to study it is by observing emission lines from the gas itself in the far infrared (FIR). With modern telescopes we are just starting to peak into the ISM of galaxies during the Epoch of Reionization (EoR), with very surprising results. My work is to invoke supercomputing powers to establish a better understanding of such observations. After a brief recap of the past few years in high-z FIR line observations, I will present the model SÍGAME; SImulator of GAlaxy Millimeter/submillimeter Emission, my main work here at the School of Earth and Space Exploration (SESE). SÍGAME builds on the output from cosmological hydrodynamic simulations of galaxy evolution to calculate the FIR line emission from different elements at any redshift desired. As examples of the method, recent results will be shown for [CII], [OI] and [OIII] of star-forming galaxies at z~6, forming part of a paper recently submitted. We find that [CII]-SFR and [OIII]-SFR power law relations come out naturally from the simulations, and I will compare with observations available at z > 5. By adopting different assumptions, we quantify how metallicity affects the [CII]-SFR relation and through a principle component analysis (PCA) we find that the the [CII] luminosity correlates most strongly with galaxy-averaged star formation rate surface density, but that molecular gas mass fraction and metallicity are also important. Finally, I will dive into future plans with SÍGAME.

Destejiendo secretos de las nebulosas Wolf-Rayet

Las estrellas masivas son las causantes principales de dar forma y enriquecer el medio interestelar (MIE) en las galaxias que vemos. Esto lo hacen debido a la combinación de diferentes factores: vientos estelares, movimientos propios, fuertes tasas de fotones ionizantes y, finalmente, como explosiones de supernova. Todos estos factores producen cavidades en elMIE que pueden ser estudiadas con observatorios de rayos X. En esta charla presento nuestroentendimiento actual de la producción de emisión difusa en rayos X en nebulosas Wolf-Rayety las implicaciones hacia otros sistemas astrofísicos.

Formación y estructura de cúmulos estelares en nubes en colapso gravitacional global

We discuss the mechanism of cluster formation in a numerical simulation of a molecular cloud (MC) undergoing global hierarchical collapse, focusing on how the gas motions in the parent cloud control the assembly of the cluster. The global collapse implies that the star formation rate (SFR) increases over time. The collapse is hierarchical because it consists of small-scale collapses within larger scale ones. The small-scale collapses consist of clumps that are embedded in the filaments and falling on to the large-scale collapse centres. The stars formed in the early, small-scale collapses share the infall motion of their parent clumps, so that the filaments feed both gas and stars to the massive central clump. This process leads to the presence of a few older stars in a region where new protostars are forming, and also to a self-similar structure, in which each unit is composed of smaller scale subunits that approach each other and may merge. Because the older stars formed in the filaments share the infall motion of the gas on to the central clump, they tend to have larger velocities and to be distributed over larger areas than the younger stars formed in the central clump. Finally, massive stars only form once the local SFR is large enough to sample the IMF up to high masses. In combination with the increase of the SFR, this implies that massive stars tend to appear late in the evolution of the MC, and only in the central massive clumps. We discuss the correspondence of these features with observed properties of young stellar clusters, finding very good qualitative agreement.

How Stars Orbiting the Lagrange Points Visit the Sun

Comparing data on the kinematics of the Solar neighborhood from TGAS Gaia DR1 to newly constructed made-to-measure dynamical models of the Milky Way we propose a novel explanation for the Hercules stream consistent with recent measurements of the extent and pattern speed of the Galactic bar. The model matches the 3D density of the Red Clump Giant stars (RCGs) in the bulge and bar as well as stellar kinematics in the inner Galaxy, with a pattern speed of 39 km/s/kpc. Cross-matching this model with TGAS Gaia DR1 data combined with RAVE and LAMOST radial velocities, we find that the model naturally predicts a bimodality in the U-V-velocity distribution for nearby stars which is in good agreement with the Hercules stream. In the model, the Hercules stream is made of stars orbiting the Lagrange points of the bar which moves outwards from the bar's corotation radius to visit the Solar neighborhood. This new picture of the Hercules stream naturally predicts that the Hercules stream is more prominent inwards from the Sun and nearly absent only a few 100 pc outwards of the Sun, and plausibly explains that Hercules is prominent in old and metal-rich stars.

A journey through the lives of local galaxies as revealed by their ionized gas and their stellar populations.

Studying the ionization sources, dynamics of the ionized gas and the interplay between it and other phases of the ISM and the stellar populations in local galaxies is essential to understand their formation and evolution. Integral field spectroscpy (IFS) is a tool that lets us study ionized gas in local galaxies with unprecedented detail. I would like to share several projects that I am involved with that make use of IFS to study different aspects of the ionized gas: the relation between nitrogen abundance (N/O) and the stellar population content of star-forming galaxies from the CALIFA survey; the locality of the effect of close interactions in the star formation of CALIFA galaxies; the presence and significance of ionized gas in early-type galaxies from MUSE data; the interplay between AGN outflows and winds and the ISM of disk galaxies from CALIFA and MUSE data, and the effect of direct, face-on collissions in the star formation and dynamics of a sample of ring galaxies from Calar Alto / CALIFA and MUSE data. All these projects contribute to the understanding of the sources and dynamics of ionized gas and its role on the evolution of galaxies in the local universe.

GAs Stripping Phenomena in galaxies with MUSE.

The so--called jellyfish galaxies are objects exhibiting disturbed morphology, mostly in the form of tails of gas stripped from the main body of the galaxy. Several works have strongly suggested ram pressure stripping to be the mechanism driving this phenomenon. GAs Stripping Phenomena in galaxies (GASP) with MUSE is an ESO large program awarded 120 hours of time with the IFU MUSE to observe galaxies with evidences of gas stripping. I will present the goal and characteristics of the survey, and show some of the first results now that 80% of the targets have been observed.

Magnetic fields and radio emission processes in water fountains and planetary nebulae

Planetary nebulae (PNe) are one of the last phases in the evolution of low/intermediate mass stars (< 8 Msun), characterized by extended diffuse ionized and neutral gas surrounding the dying hot cores. Their immediate precursors are stars in the asymptotic giant branch (AGB), characterized by a strong mass-loss, followed by a short (100-10000 yr) transitional post-AGB phase. While the morphology of the mass-loss in the AGB phase is usually spherically symmetric, PNe show complex bipolar/multipolar structures. A few post-AGB stars, the water fountains (WFs), may represent the first manifestation of collimated mass-loss in evolved stars. These sources are characterized by collimated jets traced by high-velocity water masers. The study of WFs and very young PNe is crucial to understand the variety in the morphology shown by PNe. Through polarimetric observations of maser-emitting PNe and WFs is possible to have a detailed picture of the magnetic field (structure and strength) associated with these sources. Magnetic fields are a key ingredient in the early evolution and shaping process of PNe, as well as in the stellar mass-loss. Radio continuum observations provide information about emission processes (thermal/non-thermal) associated with WFs and PNe. In this talk, I will present our recent results on polarimetric observations toward maser-emitting PNe.

Cosmologia de precision con galaxias HII y regiones gigantes HII

Informaré los ultimos resultados utilizando el estimador de distancia L(Hbeta)-sigma basado en la correlación entre las dispersiones de velocidad de gas ionizado y la luminosidad de la línea de emisión de Balmer de las galaxias HII y regiones HII gigantes para trazar la expansión del Universo a z < 3.5 con instrumentacion presente y en el futuro a z ~ 6-7 con el JWST. Este enfoque proporciona restricciones independientes sobre H0, Ωm y la ecuación de estado de la energía oscura w y de su posible evolucion en corrimientos al rojo que no son alcanzables con otros metodos (SNIa,BAO y CMB). Con respecto a H0, hemos recalibrado la muestra de anclaje de las regiones de HII gigantes en galaxias cercanas con distancias determinadas con métodos primarios vía Cefeidas y TRGB. El valor de H0 que obtenemos es intermedio obtenido por Riess et al 2016 utilizando SNIa y el resultado de la colaboracion Plank. Con respecto a Ωm y w, el uso de espectroscopia de alta dispersión Visible-NIR de galaxias HII con desplazamientos al rojo entre 0,6 y 2,7, obtenido en el VLT utilizando XShooter más algunas galaxias HII de alto z de la literatura mejora las restricciones y destaca la necesidad de perfiles de línea de emisión de alta calidad. También discutiré simulaciones basadas en estos primeros resultados que muestran que restricciones altamente competitivas a Ωm y w se pueden obtener utilizando una muestra de 500 galaxias HII de alto desplazamiento al rojo con datos de alta calidad que se pueden obtener con instrumentos como KMOS en el VLT o MOSFIRE en KECK en unas 25 a 50 noches. Nuestros ultimos datos obtenidos con MOSFIRE en KECK confirman las simulaciones y dan resultados en el plano Ωm - w de similar calidad a los que Amanullah etal 2010 obtienen utilizando la compilacion Union2 de 557 SNIa.

THE DETECTION OF INTERSTELLAR BENZONITRILE (c-C$_6$H$_5$CN) AND HC$_5$O

Dwarf Galaxy Mass Estimators vs. Cosmological Simulations

In this talk I will present results from our latest work in which we use a suite of high-resolution cosmological dwarf galaxy simulations to test the accuracy of commonly used mass estimators from Walker et al. (2009) and Wolf et al. (2010), both of which depend on the observed line-of-sight velocity dispersion and the 2D half-light radius of the galaxy, Re. The simulations are part of the Feedback in Realistic Environments (FIRE) project and include 12 systems with stellar masses spanning 10^5-10^7 M⊙ that have structural and kinematic properties similar to those of observed dispersion-supported dwarfs. Both estimators are found to be quite accurate: M_Wolf/M_true = 0.98^{+0.19}_{-0.12} and M_Walker/M_true =1.07^{+0.21}_{-0.15}, with errors reflecting the 68 per cent range over all simulations. The excellent performance of these estimators is remarkable given that they each assume spherical symmetry, a supposition that is broken in our simulated galaxies.

Seminario Doctorantes

Chemical Evolution in the Era of IFU surveys: The SDSS-IV MaNGA view

I will present the main results of our analysis of the local metallicity of the ionized gas for more than 9×10^5 star forming regions (spaxels) located in 1023 nearby galaxies included in the SDSS-IV MaNGA IFU survey. Among them, I will show the local mass - metallicity relation; its weak relation with global parameters as well as the lack of secondary relation of the global MZR with the SFR. We also explore the impact of the gas fraction in the local enrichment of MaNGA galaxies and comparisons with simple chemical evolutionary models. At kpc scales, the observed metallicity can be explained as a local version of the well-known gas regulated chemical model with outflows driven by stellar winds and SN explosions.

The quest for the largest cores in early-type galaxies

Many luminous Early Type Galaxies (ETGs; M_B < -20.5 mag) are characterized by depleted stellar cores, i.e. marked flattenings of the inner light distribution relative to the outer profile of the ETG spheroid.The structural characteristics of cores clearly depend on the formation history of the ETG, and in the last decades they have been shown to correlate with the mass of the central Super-Massive Black Hole (SMBH). This addresses to a link between the formation of the SMBH and that of the core.It has been suggested that Black Hole (BH) binaries, established during dry (i.e. gas-poor) mergers which shaped the ETG, kick stars out of the galaxian nucleus via three-body interaction, before coalescing into the central SMBH.In this talk, this "binary BH scouring scenario" is tested at its extremes by investigating the galaxies with the alleged largest cores found in the Local Universe; alternative core formation scenarios are promoted.

Latest results from SDSS-III/BOSS

Cosmic acceleration is one of the most important issues to be explored by modern observational cosmology. Cosmic acceleration can be explained by either modifying General Relativity on cosmological scales, or within the framework of the standard cosmological model this implies that ~70 per cent of the Universe is dominated by a new component called “dark energy” with the unusual physical property that opposes the attractive force of gravity. I will present the results of the Baryon Oscillation spectroscopic Survey (BOSS) that uses the baryon Acoustic Oscillation to extract information about the equation of state of dark energy. The BAO feature corresponds to the maximum distance travelled by acoustic waves in the matter-radiation fluid during the period from matter/radiation equality to their decoupling at z~1100 and then stretched by expansion of universe. This feature can be seen as a standard ruler allowing us to study the history of the expansion of the Universe and infer cosmological information. I will present the latest cosmological constraints in dark energy and extensions of LCDM that we can extract combining BAO with the cosmic microwave background (CMB) data and Type Ia supernova (SN) data.

En route to the cradle of life — Some comments on large organic molecules in space.

The nature of candidate hypercompact HII regions

Hypercompact HII regions are ionized gas regions associated with the earliest stages of high-mass star formation. These regions are characterized by their small sizes (􏰁smaller than 0.05 pc), high electron densities (larger than 1e6 cm^−3) and emission measures exceeding 1e9 pc/cm^6. Unlike ultracompact HII regions, which typically host a cluster of massive stars, hypercompact (HC) HII regions are thought to surround a single star or perhaps a binary system. As such, HC HII regions present us with a laboratory to study the physical processes involved in the formation of single stars, without the complicating phenomena of a cluster environment.In this work, we study five candidate HC HII regions originally observed at 1.3 and 3.6 cm. These regions were selected because they show 6.7 GHz methanol maser emission ( a tracer of high mass star formation) but they show little or no emission at 6 and 20 cm (indicating a pre-ultracompact HII region stage). All sources show extended 8 and 24 micron emission further supporting their identification as very young high-mass star-forming regions.To confirm the classification and to understand better the nature of these regions, we made observations at 2 and 6 cm, using the Jansky Very Large Array (JVLA) with an angular resolution of about 2 arcsec. Here we report our detections, showing the radio images and the measured parameters.We present a preliminary analysis of our results, including the modeling of the spectra as uniform and non-uniform spheres.

The evolution of the nuclear and star formation activities in compact galaxy groups over the past 3 Gyr

We present our study on the evolution of galaxy properties in compact groups over the past 3 Gyr. We are using the largest multi-wavelength sample to-date, comprised of 1770 groups (containing 7417 galaxies), in the redshift range of 0.01<z<0.23. To derive the physical properties of the galaxies we rely on ultraviolet (UV)-to-infrared spectral energy distribution modeling, using CIGALE. We find a significant increase of the number of the AGN-hosting galaxies as we are moving towards lower redshifts, and we report the absence of Seyfert 1 nuclei. We also show that at any given stellar mass, galaxies in dynamically old groups are more likely to host an AGN. Our results also suggest that during the 3 Gyr period covered by our sample, the star formation activity of galaxies in our groups has been substantially reduced (3-10 times). Moreover, their observed UV-optical and mid-infrared colours are consistent with star formation rate histories, which are significantly different from those of galaxies in the field and in clusters, as the former spend more time tran- sitioning through the green valley. We also find evidence that the morphological transformation of late-type galaxies into earlier types, occurs during the mid-infrared green valley transition rather than during the UV-optical one. Examining the emission line ratios and gas velocity dispersions of the late-type galaxies located below the star forming main sequence, we find evidence of shocks.

Resolved maps of Stellar Mass from iterative Bayesian marginalization of SPS models

Stellar masses of galaxies are frequently obtained via SPS fitting to observed photometry, or galaxy spectra. "State of the art" methods resolve spatial structures within a galaxy to asses the total stellar mass content. In comparison to unresolved studies, resolved methods yield higher fractions of stellar mass for galaxies. In this talk we will demonstrate that current methods commonly deliver biased resolved spatial structures. We will discuss the cause of this bias, an introduce a new method, based on Bayesian statistics, aimed to mitigate the bias. We applied this method to M51, and a pilot sample of spiral galaxies. We will compare quantitatively the application of both methods and discuss the results.

Ocultaciones estelares: actividades recientes en Brasil

El registro de ocultaciones estelares es la mejor técnica desde el suelo para determinar parámetros físicos de cuerpos distantes en el Sistema Solar, tales como tamaño y forma, con precisión de pocos kilómetros. Además, permite el estudio del ambiente cercano al objeto, verificando la presencia de anillos, satélites y atmósferas tan débiles cuanto algunos nanobars. Nuestra charla se concentrará en ocultaciones de estrellas por la Luna, por asteroides y por objetos transneptunianos. En la primera parte de esta charla trataremos de las particularidades y la importancia de observar cada uno de esos tres tipos de ocultaciones. Luego presentaremos algunos resultados obtenidos en Brasil en los últimos años, como en los eventos producidos por el asteroide (52) Europa (agosto de 2012), el centauro (10199) Chariklo (junio de 2013) y el planeta enano (1) Ceres (agosto de 2010 y octubre de 2013).

¿Existe Realmente la Materia Obscura?

Repasare las motivaciones astrofisicas detras de la hipotesis de la Materia Obscura, y hablare sobre el estado actual del campo. A pesar de decadas de esfuerzos dedicados, a la fecha no hay una sola deteccion de este componente, hipoteticamente dominante. Describire desarrollos recientes que indican cambios a la ley de gravedad a escalas astrofisicas, consistentes con propuestas de gravedad modificada construidas explicitamente para explicar las observaciones astronómicas sin requerir materia obscura.

Characterizing the Formation of the Most Massive Star Clusters in the Milky Way

We summarize our comprehensive gas surveys of some of the most luminous (Lbol 1e5 to 1e7 Lsun), deeply embedded (optically obscured) star formation regions in the Milky Way, which are the local cases of massive star clusters and/or associations in the making. Our approach emphasizes multi-scale, multi-resolution imaging in dust and free-free continuum, as well as in molecular- and hydrogen recombination lines, to trace the multiple gas components from < 0.1 pc (core scale) all the way up to the scales of the entire giant molecular cloud (GMC), or ~ 100 pc. We highlight our results on W49A, the most luminous Galactic star formation region (Lbol ~ 2e7 Lsun), which appears to be forming a young star cluster (or a binary star cluster) with M_star ~ 1e5 Msun that may remain bound after gas dispersal. We also highlight our recent result on the G33.92 region (Lbol ~ 3e5 Lsun), where ALMA mapping reveals that the cluster-forming accretion flow is arranged in a fragmented spiral-like structure from clump to core scales. Preliminary results in a handful of other regions will be shown.

Sobre el cinturón de Gould

El Cinturón de Gould es una de las estructuras más interesantes de nuestra galaxia, con sus ~ 10 ^ 6 masas solares de gas y estrellas jóvenes fuera del disco y colocadas apropiadamente sobre un anillo alargado de ~ 270pc y con una inclinación de ~20º respecto del disco. El estudio de la dinámica local y la evolución de esta estructura nos puede dar una muy buena idea de la dinámica y evolución de galaxias en general y también profundizar en la teoría de la formación estelar. Utilizando los datos de archivo y VLA recientes observaciones sobre el Karl G. Jansky Very Large Array se desarrolló un código semi automatico en Python / CASA para seleccionar, reducir y analizar varias estrellas jóvenes pertenecientes al núcleo de Ofiuco y nube molecular de Tauro. Este código está hecho para ayudar a seleccionar las observaciones realizadas a lo largo de los más de 30 años de servicio del VLA hechas en las regiones de formación de estelar mencionadas con las configuraciones de ancho A y B, que nos dan una mejor resolución y en las bandas X y C, donde estos objetos estelares jóvenes son más brillantes, para determinar su posición y compararla con las más recientes y de esta manera es posible determinar su movimiento propio con una precisión muy alta. Se presentan los resultados de las estrellas centrales: S1, DOAR 21, VLA1623 y YLW15 de Ofiuco, también con los resultados en las velocidades radiales, ya publicadas junto con los nuevos resultados de estrellas en la nube molecular de Tauro que es otra importante región de reciente formación estelar que pertenece a la Cinturón de Gould. Hay dos principales teorías sobre el origen Cinturón de Gould uno describe un evento catastrófico que involucró a varias supernovas, el cálculo de la energía sugieren 20 supernovas hace 30 millones de años. Este evento provocó que el gas y el polvo escaparan lejos del disco y algunos años después comenzó la formación estelar y formaron los rasgos característicos que reconocemos ahora. La segunda teoría habla sobre el impacto de una nube compacta de alta velocidad contra el disco galáctico, este impacto sacó el polvo y gas del disco dejándolo a ~20º tal como el Cinturón de Gould se muestra ahora. Ambas teorías serían distinguibles debido a las diferencias en sus movimientos propios absolutos y velocidades radiales. Estamos cerca de discernir cuál es la teoría más adecuada del origen Cinturón de Gould de entre estas últimas, teniendo en cuenta la dinámica del núcleo de Ofiuco y la región de la nube molecular de Tauro

Colisiones de agujeros negros y ondas gravitacionales

La teoría de la relatividad general fue postulada por Albert Einstein a fines de 1915. Una de sus principales predicciones son las ondas gravitacionales, perturbaciones en el espacio-tiempo que viajan a la velocidad de la luz y que se son producidas por fenómenos astrofísicos violentos, como explosiones de supernovas o colisiones de agujeros negros. Sin embargo, las ondas gravitacionales son tan débiles que tomó mas de 100 años detectarlas. En esta charla daré una breve introducción al concepto de las ondas gravitacionales, así como los emocionantes resultados relacionados con su primera detección, anunciada en febrero de 2016.

El observatorio de rayos gamma HAWC

HAWC es un observatorio de rayos gamma de gran campo de visión (1.8sr) y ciclo de operación (>95%) de capacidades únicas para el estudio de fuentes celestes de fotones de altas energías (> 100 GeV). HAWC está ubicado en la ladera norte del volcán Sierra Negra a 4100m, un kilómetro al norte del Gran Telescopio Milimétrico Alfonso Serrano con el cual comparte la infraestructura básica. Inaugurado en marzo de 2015, después de un año y medio de operaciones científicas con 1/3 del arreglo de detectores instalado, HAWC observa diariamente 2/3 de la bóveda celeste, detectando la nebulosa del Cangrejo en cada tránsito, monitoreando galaxias activas y escudriñando el Plano Galáctico.

A large scale survey of Herbig AeBe stars in Orion OB stellar Associations

We have performed a selection of intermediate mass stars (spectral types F5 or earlier) candidates that potentially exhibit protoplanetary disks based on infrared data from the 2MASS and WISE catalogs. Of particular interest are Herbig Ae/Be stars, which exhibit near infrared excesses produced in the inner wall located at the dust destruction radius and emission lines produced by accretion mechanisms. The area surveyed is ~1000 square degrees and includes the Orion OB stellar associations. Distances normally assumed for young stars located in this region range from 300 pc to 500 pc. We have initiated optical spectroscopic follow-up observations of selected candidates using the spectrographs OSU-CCDS at the observatory MDM and the Boller & Chivens at the observatory San Pedro Martir. Our main goal is to build a large scale census of protoplanetary disks around intermediate mass stars that will contribute to a better understanding of the star forming and disk evolution processes, as well as possible relationships between the environment and the spatial distribution of stars in this mass regime.

Puzzles in Galaxy Scaling Relations (or how is mass distributed around us?)

Galaxies like our Milky Way can be described in terms of their structure, dynamics, and stellar populations. Some very robust correlations between galaxy structural properties, such as total luminosity, maximum circular velocity, and size show rather small scatter, hinting at well-regulated galaxy formation processes. A major challenge to understanding these scaling relations, and ultimately galaxy formation and evolution, is the elusive interplay between visible and dark matter. I will discuss the latest constraints to galaxy scaling relations and their link with modern cosmological models.

The dust covering factor in AGN: what's wrong and how to fix it

All massive galaxies harbor a supermassive black hole in their centers. A phase during which the central black hole accretes the surrounding matter and grows considerably is referred to as the Active Galactic Nucleus (AGN). The strong radiation from the gas spiraling into a black hole is partially reprocessed by the dust clouds placed further out in a roughly toroidal shape ("the dusty torus") and is released in the infrared. Thus, the ratio of the AGN and torus luminosities (L_AGN/L_tor) is commonly used as the dust covering factor (CF) proxy. Using state-of-the-art Monte Carlo radiative transfer code, we critically investigated the relation between the L_AGN/L_tor and the CF. We found that in most of the cases L_AGN/L_tor significantly over- or underestimates the true CF. Our results provide a new straightforward way to account for the effects leading to this and obtain true CFs. We demonstrate the importance of these results for inferring the obscured fraction of AGNs as a function of L_AGN by applying the corrections to the two large samples from the literature, showing that CF has much weaker dependence on L_AGN than previously thought. Our results suggest a higher fraction of obscured AGNs at high luminosities than those found by X-ray surveys, partially due to the presence of a Compton-thick AGN population, which is missed by X-ray surveys, but not by infrared.

Modelos auto-consistentes de fotoionización para la Nebulosa Planetaria NGC6826 y el FLIER Noroeste

Un problema persistente en la astrofísica nebular es la determinación de las abundancias químicas de una nebulosa fotoionizada, principalmente porque se requieren determinaciones precisas de la densidad (Ne) y la temperatura electrónicas (Te). También existe el problema de que la determinación de las abundancias químicas mediante diferentes métodos empíricos arroja diferentes resultados. Una manera de solventar este problema es confrontando las observaciones con las predicciones de modelos teóricos, en particular de fotoionización. Aunado a ello, desde los años 90 se observaron, dentro de las Nebulosas Planetarias, estructuras bipolares cuya emisión en [N II] era mucho más fuerte que el resto de la nebulosa (FLIER, Fast Low Ionization Emission Region). Desde entonces existe una discrepancia en la determinación de las abundancias químicas de estas estructuras, y por lo tanto, del escenario de su formación y evolución. En este trabajo se presenta la determinación de abundancias de la Nebulosa Planetaria NGC6826 y del FLIER NW a partir de la confrontación de observaciones de espectroscopía óptica con modelos autoconcistentes 1D de fotoionización tomando en cuenta tres escenarios diferentes de evolución de los FLIERS.

Particle acceleration and magnetic field amplification in the hotspots of FR II radiogalaxies

One of the most exciting and unsolved problems in Astrophysics is figuring out the origin of the Ultra High Energy Cosmic Rays. These are particles having an energy of about 100 EeV (which is a billion times the energy of the Higgs boson) and arrive on the Earth from outside the Galaxy, but their origin remains unknown. It has been suggested that relativistic shocks in extragalactic sources like Active Galactic Nuclei may accelerate the highest energy cosmic rays. The maximum energy to which cosmic rays can be accelerated depends on the structure of magnetic turbulence near the shock but recent theoretical advances indicate that relativistic shocks are probably unable to accelerate particles to energies much larger than 1 PeV. We study the hotspots of powerful radiogalaxies, where electrons accelerated at the termination shock emit synchrotron radiation. The cut-off of the synchrotron spectrum is typically observed between infrared and optical frequencies, indicating that the maximum energy of non-thermal electrons accelerated at the shock is about 1 TeV for a canonical magnetic field of 100 micro Gauss. Based on theoretical considerations we show that this maximum energy cannot be constrained by synchrotron losses as usually assumed, unless the jet density is unreasonable large. We test this result by considering a sample of hotspots observed with high spatial resolution at radio, infrared and optical wavelengths.

How Old Are Young Stars?

Despite many decades of theoretical effort and large volumes of high-precisionobservations, obtaining ages for stars accurate to within ~10% remains a difficult and often elusive challenge for stellar astrophysics. In constrast, cosmologists can claim a precision of 1% for the age of the Universe! In this talk I provide a general overview of the various techniques at our disposal to estimate the ages of young, nearby stars. I will adopt a hierarchial approach in this review, in order of decreasing precision and/or utility. Firstly I will examine "semi-fundamental" techniques that rely on well-understood physics - the lithium depletion boundary method and kinematic tracebacks. Next I will discuss the "model-dependent" methods that are subject to various inputs in the stellar physics - the isochronal method, upper main-sequence fitting and asteroseismology. Finally I will describe the "empirical" methods, which rely on, at their very least, a non-monotonic age-functional form that is often poorly constrained - rotation, activity and lithium in FGK stars. In my summary I provide a forecast for future stellar chronometry, focusing on the prospects expected from the GAIA mission which should provide micro-arcsecond precision astrometry (due for first data release in Summer 2016).

Nuevo Programa de Posgrado en Astrofísica de la UNAM

Presentaré las principales características del Plan de estudios de la Maestría y el Doctorado en Astrofísica que se implantará en el semestre 2017-1 (agosto-diciembre 2016). Hare incapie en las modificaciones mas relevantes de ambos planes de estudios: 1) Maestria: requisitos de ingreso y modalidades de graduación. 2) Doctorado: Requisitos de ingreso.

The Billion Star Galactic Surveyor.

The Gaia mission will provide us with an unprecedented stereoscopic map of the heavens and will likely be the astronomical data resource for decades thereafter, representing a tremendous discovery potential. It will measure parallaxes and proper motions for every object in the sky brighter than magnitude 20 - amounting to 1 billion stars, galaxies, quasars and solar system objects. I will summarise the Gaia mission, performance so far and some early discoveries. The complexities of the final Gaia catalogue, and the science we want to extract from it, will force us to be very ambitious in the way we publish the Gaia catalogue. In order to unlock the full potential, we need to integrate the Gaia catalogue with other sky surveys and provide advanced statistical approaches and visualisation tools to allow the community to explore the data, do the science they expect and to facilitate the discovery of the unexpected. I will mention some of the efforts that are being undertaken within the scientific community to tackle these aspects and how these along with the Gaia data will be made available.

Ring Nebulae: Tracers of the CNO Nucleosynthesis in Wolf-Rayet Stars

Ring nebulae are interstellar bubbles of ionized gas that have swept-up the surrounding interstellar medium after the mass loss episodes experienced by their massive progenitors, especially during the Wolf-Rayet phase. The presence of stellar ejecta in ring nebulae allows us to better understand the nucleosynthesis of massive stars and the effects of the H-burning reactions on the elements involved in the CNO cycle. A detailed analysis of the chemical composition and abundance ratios of these elements provides us valuable information to constrain stellar evolution models of massive stars and the evolutive scenario of the stellar progenitors. Within this framework, we will present results from new spectroscopic data in the optical range of the Galactic ring nebulae NGC6888, G2.4+1.4, RCW58 and NGC7635 based on very deep observations obtained with the 10m GTC telescope and the 6.5m Clay telescope. In comparison with previous studies, these new observations have allowed us to derive physical conditions and chemical abundances with great accuracy in different zones of the nebulae. Therefore, we have been able to detect and localize areas of shocked gas, and investigate the presence of chemical inhomogeneities in these objects. Additionally, we will present the first determinations of C abundances in these ring nebulae based on the faint recombination line CII 4267 A as well as their implications when comparing with the predictions of stellar evolution models. These crucial results represent the first constrains on C abundances, providing long-awaited information on the action of the CNO cycle that controls the nucleosynthesis processes in massive stars.

Seminario doctorantes

Spectroscopic analysis of FGK-type stars in the era of large surveys

Spectroscopy, as a tool, has permitted some of the most fundamental discoveries in the study of the Milky Way. With the growing number of Galactic surveys (e.g. the Gaia-ESO survey, GALAH, APOGEE) in medium and high resolution, the number of stars observed will amount to several hundred thousands in the near future requiring precise analyses of their spectra in terms of their atmospheric parameters and chemical abundances. In this talk, I will present the main spectroscopic methods for the derivation of the stellar atmospheric parameters (namely the effective temperature, surface gravity, metallicity) and the fields where stellar characterization plays a key role. In particular, these tools enable us to distinguish and define the different stellar populations our Galaxy is composed of. I will also describe why this work comes in good time for the analysis of the Gaia data, a very anticipated mission for the study of our Galaxy.

Multiple generation of stars inside star clusters, an open question

For decades we have understood the star clusters as a bound association of stars that share their age and their metallicity. This was due to the understading that stars inside a star clusters formed from the same mother cloud. However, during the past ~10 years new observations have been challenging this idea. Multiple stellar populations have been observed inside particular star clusters, where stars with different metallicities have formed in large numbers inside clusters. In this seminar, I will present the background of this open problem in the field and the possible solutions to this problem.

X-ray reverberation signatures in the X-ray variability of AGN

During the last 30 years spectral studies of the broad iron K-alpha line and the Compton hump in the X-ray spectra of AGN have shown that the X-ray source illuminates the innermost part of the accretion disc in these systems. Further support to this hypothesis is provided by the detection of delays between the X-ray continuum variations and the spectral features that are supposed to be produced by X-ray reflection (mainly the soft-excess and the iron line). The X-ray reprocessing by the disc should also affect the X-ray continuum variability properties. The observed X-ray power-spectra should show a prominent dip at high frequencies and an oscillatory behaviour, with a decreasing amplitude, at higher frequencies. These reverberation “echo” features should be more prominent in energy bands where the reflection component is more pronounce, and should depend mainly on the central black hole mass and the X-ray source height. The detection of the X–ray reverberation signals in the PSDs can provide further evidence for X-ray illumination of the inner disc in AGN and can be used to map out the geometry of the inner accretion flow (which cannot be studied in any other way).

eROSITA synthetic simulations of the extragalactic sky: cluster selection function and cluster counts forecasts

I will present forecasts on galaxy cluster counts from the X-ray survey with the future eROSITA mission. Clusters of galaxies are the largest gravitationally-bound objects in the Universe. Thereby clusters are ideal tracers of cosmic expansion and structure formation that allow tight constraints on the average cosmic density of matter and of other fundamental cosmological parameters. In this talk I will show how we study the detection efficiency of galaxy clusters of the upcoming eROSITA X-ray mission. The cluster detection probability is investigated by means of extensive and dedicated Monte Carlo simulations, and employing a state-of-the-art source detection technique we determine a cluster detection e_x005F_x000e_efficiency based on the cluster fluxes and sizes. Using this eROSITA cluster selection function, we found that eROSITA will be able to detect a total of _x005F_x0018_ 1.36x_x005F_x0002_10^5 clusters in the whole sky. This cluster number will allow eROSITA to put stringent constraints on the dark matter and dark energy models.

The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet_x005F_x0092_s Perturbations

Potentially habitable planets within the habitable zone of M-dwarfs are affected by tidal interaction. We studied the tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of the dynamical evolution focusing on the effects that a rheological treatment, different compositions and the inclusion of orbital perturbations, have on the spin-down time and the probability to be trapped in a low spin-orbit resonance. Composition have a noticiable effect on the spin-down time, changing, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time to reach a low resonance value (3:2) for the configuration of 6 planets. Capture probabilities are affected when assuming different compositions and eccentricities variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and nothing on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.

Análisis de la emisión milimétrica molecular en regiones de formación estelar de alta masa y estudio teórico de la formación de CH3CHO

En este seminario hablaré del trabajo que presenté para mi tesis de licenciatura en la Universidad Autónoma de Barcelona para obtener los títulos de Graduado en Física y Graduado en Química. El trabajo consta de una parte dedicada a la Radioastronomía y otra parte dedicada a la Química Cuántica. En la primera parte, presentaré observaciones de líneas moleculares de 26 regiones de formación estelar de alta masa, que cubren diferentes estados evolutivos. Dichos espectros fueron tomados con el radiotelescopio IRAM-30m y cubren una banda de 16 GHz. Mostraré los ajustes de los espectros hechos con XCLASS para obtener los parámetros físicos de las regiones, y daré una primera idea de la química que caracteriza cada estado evolutivo. En cuanto al trabajo de química, presentaré las herramientas computacionales químico-cuánticas que he usado para diseñar la formación del CH3CHO usando dos modelos de reactividad, ambos tanto sobre superficies de hielos de agua como en fase gas. Finalmente, relacionaré las conclusiones de los modelos químico-cuánticos con los resultados observacionales presentados en la primera parte.

Optical/infrared interferometry and the study of massive stars

During the last decade, the use of optical/infrared interferometry has grown up to study stellar physics. Facilities like the Very Large Telescope Interferometer (VLTI) in Europe, or the CHARA array in the United States have proven to play a key role to perform high-angular resolution observations. The scientific cases addressed with this technique go from the study of (massive) young stellar objects to multiple systems or evolved stars. In this talk, I will perform a review of the basic principles of the optical/near-infrared interferometry and of the current European facilities to use this observational technique. Particularly, I will describe the main differences between radio and infrared interferometry (e.g., the observables and the problem of image reconstruction). I will provide a review of the current (and future) instruments available at the ESO VLTI, enhancing their advantages and limitations. Finally, as a show case, I will present my current studies of massive stars using this technique, paying special attention to the characterisation of multiple systems and of the winds of the massive stars at the Galactic Center.

A comprehensive comparative test of seven widely used spectral synthesis models against multi-band photometry of young massive-star clusters

We test the predictions of spectral synthesis models based on seven different massive-star prescriptions against Legacy ExtraGalactic UV Survey (LEGUS) observations of eight young massive clusters in two local galaxies, NGC 1566 and NGC 5253, chosen because predictions of all seven models are available at the published galactic metallicities. The high angular resolution, extensive cluster inventory, and full near-ultraviolet to near-infrared photometric coverage make the LEGUS data set excellent for this study. We account for both stellar and nebular emission in the models and try two different prescriptions for attenuation by dust. From Bayesian fits of model libraries to the observations, we find remarkably low dispersion in the median E(B - V) (~0.03 mag), stellar masses (~10^4 M⊙), and ages (~1 Myr) derived for individual clusters using different models, although maximum discrepancies in these quantities can reach 0.09 mag and factors of 2.8 and 2.5, respectively. This is for ranges in median properties of 0.05-0.54 mag, 1.8-10 × 10^4 M⊙, and 1.6-40 Myr spanned by the clusters in our sample. In terms of best fit, the observations are slightly better reproduced by models with interacting binaries and least well reproduced by models with single rotating stars. Our study provides a first quantitative estimate of the accuracies and uncertainties of the most recent spectral synthesis models of young stellar populations, demonstrates the good progress of models in fitting high-quality observations, and highlights the needs for a larger cluster sample and more extensive tests of the model parameter space.

Molecular Clouds: A Collapsing Paradigm

I review the evolution of our understanding on the nature, structure and dynamics of molecular clouds (MCs). I start with the first observations of molecular and the quick realization that they imply supersonic motions in MCs, which initially were interpreted as gravitational collapse. However, it was soon argued that global collapse of the clouds would imply a SFR larger than observed by two orders of magnitude. Then it was proposed that MCs were supported against collapse by some agent causing them to survive for much longer times than their free-fall times. I then review the two main paradigms of cloud support: magnetic and turbulent, discussing their basic features, and the reasons leading to their demise. Finally, I discuss the evidence that in the last half-decade has suggested a return to the global collapse scenario, and how the SFR is regulated in this case.

A Panchromatic view of Born-again planetary Nebulae

Born-again planetary nebulae (PNe) represent unique objects in the evolution of thecircumstellar medium around low-mass stars (M < 8 Msun). The central starsof these PNe are thought to have experienced a very late thermal pulse when they were in the white dwarf track that produced the ejection of newly processed material inside the old PN. This scenario offers the opportunity to study the wind-wind interaction and production and destruction of molecules and dust in human scales (~20-100 yr). In this talk I present a review of our multi-wavelength campaign to characterise bona-fide born-again PNe using ground-based telescopes and satellites.

The dusty tori of nearby QSOs: a high angular resolution view

Despite much effort has been devoted to characterize the dusty tori in active galactic nuclei (AGN), very little is still known in those with high bolometric luminosity, mostly quasi-stellar objects (QSOs). This is mainly due to their compactness and sparseness in the local Universe. Mid-IR high angular resolution observations offer a good oportunity to step foward in their understainding. In this talk, I going to present new high angular resolution mid-IR data (0.3 arcsec) obtained with the IR camera CanariCam (CC) on the 10.4m Gran Telescopio CANARIAS, for a sample of 20 nearby QSOs. The analysis of the images at Si2 band (8.7 um) reveals that the mid-IR emission is unresolved in the majority of QSO at scales < 600 pc. We compare the IRS/Spitzer and the ground-based CC spectra and find that the spectral shapes are similar, and hence adopt the former to isolate the AGN component. We find that on average the AGN contributes 85 per cent of the total mid-IR emission within the IRS/Spitzer apertures (~3.5 arcsec), while the rest can be atribbuted to starburst emission. We use unresolved near-IR emission from the literature and the starburst-subtracted mid-IR spectra to constrain the physical and geometrical parameters of clumpy dusty torus models of Nenkova et al. We find that for most QSOs the unresolved SED and spectroscopy can be well reproduced by the models without the inclussion of a hot dust component, as propose in the literature. Finally, a statistical comparison between the parameters of the dusty torus of QSOs derived by us and the dusty torus of some Seyfert 1s and 2s studied with a similar technique for others authors, shows that the properties of the dusty torus in QSOs are intrinsically different from those of Seyfert 1 and 2 nuclei. Nevertheles, in QSOs the parameters derived (e.g., the covering factor) are consistent with the optical classification of QSOs as type 1 AGN. An analysis on the dependence of the covering with the bolometric luminosity suggests that these differences can be attributed to dusty structures that have been partly evaporated and piled up by the higher intensity radiation field in QSOs, as proposed by a receding torus scenario.

Una gráfica de exclusión cosmológica para EUCLID

Uno de los objetivos que tiene la misión EUCLID es el estudio de la naturaleza de la energía oscura, para lograr esto es necesario contar con métodos que nos permitan realizar un análisis lo más general posible. Uno de los marcadores más claros que distinguen LCDM de modelos alternativos es lo que se conoce como el estrés anisotrópico η = −Φ/Ψ. En esta plática presentaré las constricciones actuales y futuras para este marcador usando un método que es independiente tanto del modelo como de la evolución cósmica en el rango de observación y del bias. Por otro lado construiremos una gráfica de exclusión, similar a las utilizadas en experimentos de gravedad hechos en laboratorio, con base en el pronóstico de observaciones bajo las especificaciones de EUCLID y adoptando una forma general de η que abarca todas las teorías dentro de la formulación de Horndesky, encontraremos así qué tan bien las mediciones futuras de agrupamiento de galaxias, de H y de lente débil podrían constreñir su valor tomando como modelo de referencia LCDM. Finalmente mostraremos cómo extender este método cuando utilizamos un modelo de referencia alternativo, en particular f(R).

GALAXY BULGES AS TRACERS OF GALAXY FORMATION: Clues to the origin of field lenticular galaxies

The relevance of galaxy bulges as central pieces in the study of galaxy formation is nowadays well settled. Bulges come in two flavours: classical and disk-like bulges. Different formation mechanisms have been proposed to explain this dichotomy and therefore understanding their demography is of vital importance to unveil galaxy formation. In this talk, I will present the results of a careful photometric analysis of the galaxies present in the CALIFA survey. Using the available SDSS photometry, we found a zoo of morphological structures (single and double bars, broken exponential profiles, etc), with bulges following this diversity in terms of a wide range of masses and concentrations (i.e., Sersic index). In particular, I will focus on the observed properties of bulges in lenticular galaxies where, by definition, they are suppose to play an important role in their evolution. Combining the photometric analysis of the galaxy bulges with the stellar kinematic information about their rotational support (angular momentum), we suggest that lenticular bulges were mainly formed through dissipational processes at high redshift, either wet major mergers or coalesce of giant star-forming clumps. I will discuss these results in the general context of lenticular galaxies formation.

Observing Planet Formation with the VLA in the era of ALMA

We are at present in an very exciting era for the study of how planets form. During the previous decades, observations with powerful radiointerferometers, specially the Very Large Array (VLA), have well established that planet formation is a natural consequence of the star formation process itself. Planets are most probably formed as dust evolve in the circumstellar disks around Young Stellar Objects (YSOs). It is now that, the extraordinary observing capabilities of the Atacama Large Millimeter Array (ALMA) are offering us an unprecedent level of detail of circumstellar disks around YSOs. The recent ALMA observations with very high angular resolutions of several disks are revealing several structures, consequences of the dust evolution, and most probably associated with the initial stages and/or ongoing planet formation. However, the contribution of the VLA to this field has not yet finished. Instead, the VLA with its recent upgrade, is still in the race and it is indeed revealing itself as a fundamental instrument to investigate the planet formation process. It seems necessary to still observe at longer millimeter wavelengths than ALMA in order to be able to penetrate very dense regions in the disks. This is specially critical at the earliest stages and at the innermost parts of the disks where, for example, terrestrial planets are expected to form. Here, I will present some very recent observations with the VLA of two very young circumstellar disks (HL Tau and HD 169142). I will also discuss how the combination of VLA and ALMA images is what actually could provide a giant step in the understanding of the planet formation process.

Brotes estelares maximales en galaxias en formación

Se describen los censos del cielo extragaláctico trazados en ondas milimétricas con la instrumentación del Gran Telescopio Milimétrico Alfonso Serrano (GTM), que nos han permitido encontrar galaxias lejanas con brotes de formación estelar que exceden las 1000 masas solares al año en áreas de alrededor de 3 mil años-luz de diámetro. Estos extraordinarios sistemas probablemente forman estrellas en un regimen ligado por gravedad, en el que el material que eyectan las estrellas no puede formar un viento galáctico que frene la formación estelar, sino que se recicla para formar nuevas generaciones de estrellas. Se presenta la evidencia para sostener que estas galaxias son probablemente los progenitores de la población de galaxias elípicas masivas del universo local.

The ALMA view of the explosive outflow in Orion KL: Relics from a violent merger?

In this talk, I will show the recent results obtained in deep ALMA observations of the explosive outflow located in the heart of the Orion Nebula, the Orion Kleinmann-Low Nebula (Orion KL). These observations revealed over a hundred arcsecond wide and tens of arcseconds long high-velocity 12CO (J=2−1) streamers that approximately point to a central region where a young stellar massive system disintegrated very recently. The kinematics and morphology of the molecular streamers confirmed the explosive nature of the outflow in Orion KL. The energetics of the explosive outflow require the formation of a binary with an AU-scale or smaller semi-major axis. This event may have led to stellar merger which powered the explosion in the gas. Finally, I will show the latest efforts to reveal more cases where possible mergers events could led explosive outflows like the one in Orion KL.

Exploring the environment of AGN by Spectropolarimetry observations

I present an observational study of a sample of radio AGN sources. I study their radio polarization properties in a wide frequency range by observing with the 100-m Effelsberg telescope and the Very Large Array (VLA) interferometer. The aim was 1) to define a sample of candidates to contain an extreme environment around the SMBH and, 2) to study their environment by modeling of the polarization properties within a wide frequency range. I select sources with no detectable flux polarization at 1.4GHz in the NVSS survey, characteristic of strong depolarization due to a high value of Rotation Measure (RM) and thus, of an extreme medium in these sources. I performed single dish observations at 10.45 GHz using the 100-m Effelsberg telescope. At this high frequency, I detected polarized flux density on 30 sources, which became our high-RM candidates. Single dish follow-up in the 2 to 15 GHz frequency range, were performed to characterize their radio spectra and to determine their RMs. The polarization angle behavior deviates significantly from the lambda^2 law, suggesting that several Faraday screens are present in the intervening medium. I studied the most interesting high-RM cases through wide-band high sensitive observations at C and X bands using the JVLA. I modeled the polarization properties constructing a set of models which are combinations of simple internal and the external Faraday screens. This new approach of polarization study allows to spectrally resolve multiple polarized components of unresolved AGN with the result to trace some clumpy and dense region surrounding them. This new spectropolarimetry approach can be adopted as a new way to trace clumpy and dense regions surrounding the AGN. Moreover, I will present a new project I am involved in which this new spectropolarimetry study is applied to a very specific class of objects: the Compact Symmetric Objects (CSOs), the nature of which is still matter of debate. Indeed, whether they are young radio sources (youth scenario) or compact radio sources embedded in a very dense medium (the frustrated scenario), is not clear yet. The Stokes Q and U modeling will help to understand which of the two scenario is the most probable. I will explain the “engulfed cloud model”, proposed by Begelman 1999 which is in favor of the youth scenario and that it could be tested with this new spectropolarimetry approach.

Tasas de perdida de polvo de AGBs en la vecindad Solar

Las estrellas AGB contribuyen de manera importante a la tasa total de masa de polvo que es inyectada al MIE de las galaxias. Estimaciones de esta inyeccion han sido hechas para el caso de las Nubes de Magallanes, usando observaciones del telescopio Spitzer. Sin embargo, la ultima estimacion de la tasa de inyeccion de polvo en la Via Lactea fue hecho a finales de los ochenta, para una muestra que no cubre todo el cielo. En este trabajo revisamos la tasa total de perdida de polvo de estrellas AGB en la vecindad solar. Es especialmente dificil obtener distancias a estrellas AGB 'polvosas', ya que no se encuentran en los catalogos de Hipparcos, debido a la alta exticion en su medio circunestelar. Usando los catalogos de WISE, 2MASS y otros, construimos distribuciones de energia a varias longitudes de onda para todas las estrellas AGB localizadas a una distancia maxima de 1 kpc. Para el calculo de la tasa de perdida de masa, usamos la malla de modelos GRAMS. En esta platica mostramos resultados de el numero total de estrellas AGB en la vecindad solar y su tasa total de perdida de masa. Tambien mostramos una comparacion entre las distancias de brillo que obtenemos y las reportadas en la literatura usando varias tecnicas observacionales.

Desgarramiento de estrellas por agujeros negros supermasivos

Se piensa que prácticamente todas las galaxias alojan un agujero negro supermasivo en sus centros. No obstante, la evidencia directa que tenemos sobre su existencia es escasa puesto que la mayor parte de estos objetos se encuentran en una fase inactiva. Una oportunidad única para estudiar a esta población de agujeros 'durmientes' se presenta ocasionalmente cuando una estrella se acerca lo suficiente al agujero negro central y es desgarrada por las fuerzas de marea de éste. En esta plática presentaré características tanto teóricas como observacionales de este tipo de fenómenos. Así mismo discutiré algunos de los retos que se presentan al estudiar estos encuentros numéricamente y presentaré ejemplos de simulaciones recientes que modelan un evento de este tipo de principio a fin.

La tasa de fusión entre galaxias en la simulación cosmológica Illustris

En el modelo cosmológico actual (Lambda-CDM) la estructura crece jerárquicamente, por lo cual las fusiones entre galaxias son un ingrediente esencial de cualquier modelo de formación de galaxias. Una determinación precisa de la tasa de fusión entre galaxias es necesaria para explicar la distribución morfológica de las mismas, así como la frecuencia de objetos muy luminosos en el Universo temprano, como galaxias con brotes de formación estelar y núcleos activos de galaxias. Aunque la tasa de fusión entre halos de materia oscura ya está determinada con bastante precisión, gracias a avances en simulaciones de N cuerpos durante la primera década del milenio actual, hace falta una medición igualmente precisa de la tasa de fusión entre galaxias, ya que distintas predicciones teóricas presentan diferencias de alrededor de un orden de magnitud entre ellas.

En este estudio hemos usado simulaciones del proyecto Illustris, un conjunto de simulaciones hidrodinámicas de gran escala realizadas con el código de malla móvil AREPO, para construir árboles de fusiones de galaxias y con ellos calcular la tasa de fusión entre galaxias como función de la masa estelar del descendiente, el cociente entre las masas de los progenitores, y el corrimiento al rojo. Encontramos que la tasa de fusión entre galaxias tiene una forma matemática relativamente sencilla y que su evolución con respecto al corrimiento al rojo es consistente con observaciones de pares de galaxias medianas (M* > 10^10 Msun). La variación de la tasa de fusión con respecto a la masa estelar de la galaxia descendiente es consistente con observaciones recientes del estudio GAMA (GAlaxy and Mass Assembly). Finalmente, proporcionamos una función analítica para la tasa de fusión que es precisa sobre un rango amplio de masas estelares, cocientes de masa y corrimientos al rojo.

APOGEE-2: la Galaxia al alcance de tus dedos

La UNAM entró en 2012 a la cuarta fase del catastro Sloan Digital Sky Survey (SDSSIV), como miembro del consorcio con todos los privilegios. Siendo uno de los proyectos más productivos en la astronomía en las últimas décadas, nuestra participación representa una gran oportunidad. En esta charla hablaré de uno de los cuatro proyectos principales del SDSSIV, llamado Apache Point Galactic Evolution Experiment (APOGEE-2) cuya segunda fase recién comenzó. APOGEE-2 es un catastro espectroscópico en alta resolución, en el cercano infrarrojo, de todas las componentes galácticas, basado principalmente en estrellas gigantes (cerca de 0.25 millones de fuentes), pero que se extiende incluso a estrellas tardías (enanas tipo K y M) y a estrellas muy jóvenes en regiones de formación estelar. Hablaremos de las generalidades del consorcio SDSS, de las metas y sub-proyectos de APOGEE-2, y de cómo podemos (y debemos) participar en él.

The Herschel Exploitation of the Local Galaxy Andromeda (HELGA): the relations between dust, gas and stars in M31

I am presenting the results from the "Herschel Exploitation of the Local Galaxy Andromeda" (HELGA), a survey who observed our neighbour galaxy M31 in five IR bands. Taking advantage of Herschel sensitivity and spatial resolution, we address various issues related to the dust distribution and properties in Andromeda, and its relation to the spatial distribution and characteristics of the gas and stellar components. Dust in M31 extends well beyond its optical radius, and is gathered in well-defined recurrent patterns. Contrary to what is found in other galaxies, dust reaches the highest temperatures in the bulge, heated by the old stellar populations, and its (chemical) properties change radially. Using a panchromatic dataset we adopt physically consisted panchromatic model to fit the broad-band SED of each pixel in our data, to address the origin of dust scaling relations, at the spatial level of giant molecular clouds.

Shape - un laboratorio astrofísico virtual interactivo

Mostramos algunos resultados representativos de aplicaciones recientes del software Shape. En los últimos años este programa se ha convertido en un laboratorio astrofísico virtual interactivo con un espectro de aplicaciones muy amplio. Su aplicación principal es el modelado tridimensional para analizar e interpretar observaciones de objetos particulares en base al modelado manual en un espacio 3D virtual. Además, el programa incluye un módulo de hidrodinámica básica, transporte radiativo y básicas funciones de fotoionización, entre otros.

La interactividad permite su aplicación cómo herramienta demostrativa visual en clases de astrofísica ilustrándose de manera directa una amplia gama de fenómenos astronómicos teóricos y observacionales. Una característica clave de Shape es que el usuario no necesita interactuar con el código del programa. Todas las funciones de realizan mediante la interfaz gráfica.

Acreción de Bondi-Hoyle-Littleton y el extremo superior de masa de la FMI

Mediante el uso de simulaciones numéricas de grumos densos y masivos con fluctuaciones iniciales de velocidad y/o densidad, mostramos que la función de masa de las partículas sumideros sigue una ley de potencias con pendiente $dN/d\log M \propto M^{\Gamma}$, $\Gamma = -1 \pm 0.1$, independientemente del número de Mach inicial. Esta dependencia concuerda con el límite asintótico encontrado por Zinnecker suponiendo acreción de Bondi-Hoyle-Littleton (BHL). Aunque la acreción BHL no es aplicable estrictamente debido a la complejidad y variabilidad del ambiente que rodea a cada partícula sumidero, argumentamos que las FMI son el resultado de una dependencia de la tasa de acreción con $M^2$, al menos por grupos de estrellas. Aunque hemos simplificado la ecuación de estado, y evitado procesos adicionales como transferencia radiativa y calentamiento estelar, nuestras simulaciones enfatizan la importancia del enfocado gravitacional para la formación estelar masiva.

Simulaciones MHD en 3D de la emisión polarizada del remanente de la SN 1006

Modelamos el remanente de la SN 1006 mediante simulaciones magnetohidrodinámicas en 3D. A partir de los resultados numéricos, hicimos un estudio de la emisión polarizada en radiocontinuo, obteniendo mapas sintéticos de la emisión polarizada, el parámetro de Stokes Q y del ángulo de posición del campo magnético, los cuales se comparan con las observaciones. En el cálculo de la emisión en sincrotrón, consideramos los dos posibles mecanismos de aceleración de las partículas relativistas: el cuasiparalelo y el cuasiperpendicular. La comparación de nuestro mapa sintético del parámetro Q con el observado, muestra que el mecanismo de aceleración responsable de la emisión en radio de este remanente es el cuasiparalelo, removiendo la ambigüedad que había en estudios previos.

Gravity or turbulence? Dynamics, fragmentation and cloud structure

Traditionally its been considered that turbulence in molecular clouds provides support against self-gravity. In order to do so, turbulence should be random, microscopic and isotropic. However, it is highly uncertain which sources of energy may provide such kind of turbulence, since it is highly dissipative, and most of the energy is involved at the largest scales, which furthermore, imply that it cannot be isotropic. In the present contribution we will discuss a set of observational and theoretical results, namely, the column density PDF, scaling relations, fragmentation of clouds into clumps and clumps into cores, formation and evolution of clouds and cores, Virial type relations, etc., which strongly suggest that nonthermal motions within molecular clouds, rather than kinetic energy providing support against collapse, might be very well the result of hierarchical and chaotic collapse

Cosmic rays injected by runaway stars in open clusters

Some young open clusters and giant molecular clouds have been detected as gamma-ray sources in recent years. The level of gamma radiation suggests the existence of local injectors of cosmic rays in these objects. I will discuss the contribution of massive runaway stars and other supersonic objects to the cosmic ray population in young clusters and the origin of the observed gamma-ray emission.

El medio ambiente de galaxias barradas a diferentes escalas

Empleando una muestra limitada por volumen de mas de 30,000 galaxias proveniente del SDSS DR7, hemos investigado el medio ambiente de galaxias barradas, empleando un variado conjunto de estadísticas. Al dividir nuestras galaxias de acuerdo a su tipo morfológico, encontramos que las galaxias barradas de tipo temprano muestran una tendencia débil pero significatíva a sobreagruparse en escalas entre 100 kpc a 1 Mpc cuando comparamos su distribución con galaxias de tipo temprano no barradas, lo cual indica que la presencia de barras en galaxias de tipo temprano depende de sus posiciones dentro de los halos de materia obscura que las contienen. Para galaxias barradas tardías, encontramos que presentan menos vecinas cercanas en escalas menores a 500 kpc que sus similares no barradas, lo que sugiere que fuerzas de marea de compañeras cercanas suprimen la formación/evolución de las barras. Para galaxias centrales de tipo tardío encontramos que la fracción de galaxias con barras fuertes depende fuertemente tanto del espín galáctico como del cociente masa estelar/masa del halo, de forma que las galaxias con valores entre bajos a intermedios de espín y con discos estelares relatívamente masivos en relación a sus halos de materia obscura, presentan fracciones de galaxias barradas mas altas que aquellas con altos valores de espín y bajos valores del cociente masa estelar a masa del halo obscuro. Finalmente, no encontramos ninguna relación obvia entre la presencia de barras estelares en galaxias con la estructura a gran escala del Universo.

Discos de acreción alrededor de un agujero negro con energía oscura presente

Se presenta una extensión de la Relatividad General en la cual se propone que la masa no solo curva el espacio sino también cambia la estructura del vacío. Esto resulta en la presencia de una energía oscura cuya densidad aumenta hacia menores distancias radiales. El efecto tiene su justificación en la Mecánica Cuántica semi-clásica, pero también resulta de una teoría propuesta por nosotros, llamada Relatividad General seudo-compleja. La presencia de la energía oscura tiene una influencia importante sobre la apariencia del disco de acreción para un observador muy lejos. Presento una breve introducción a la teoría de Relatividad General seudo-compleja y posteriormente una descripción para el disco de acreción de Page y Thorne. Una de las predicciones importantes es la apariencia de un anillo oscuro en el disco de acreción.

Emisión de rayos X de Nebulosas Planetarias: Simulaciones, Observaciones y el proyecto CHANPLANS

En esta charla presentamos nuestros resultados numéricos más recientes sobre la emisión de rayos X de Nebulosas Planetarias. Para esto, desarrollamos simulaciones radiativo-hidrodinámicas en 2D de alta resolución para estudiar la formación y evolución de burbujas calientes en estos objetos. Tomamos en cuenta la evolución detallada de la estrella central y sus parámetros estelares desde los últimos pulsos térmicos durante la etapa de la rama asintótica de las gigantes (AGB) hasta la etapa post-AGB para diferentes masas iniciales. Utilizamos el código CHIANTI para calcular los parámetros observables en rayos X (espectros sintéticos, luminosidades, temperaturas, etc) para comparar directamente con observaciones. En particular, hacemos una comparación directa con los resultados observaciones del proyecto CHANPLANS (The Chandra Planetary Nebula Survey).

Vertical Structure of Magnetized Accretion Disks Around Young Stars

We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, irradiation by the central star and magnetic pressure. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field developed by Shu and coworkers. We consider disks around low mass protostars, FU Ori and T Tauri stars. We tested our formalism using different mass-to-Magnetic flux ratios and I will show how this essential parameter can strongly modify the disks structure.

A multifrequency study of large radio sources

We present the results of our mutlifrequency observations with the GMRT and the VLA of five large radio galaxies. These observations were made with the objectives of estimating their spectral ages and examining any evidences of diffuse extended emission at low radio frequencies due to an earlier cycle of

activity. While no evidence of extended emission due to an earlier cycle of activity has been found, the spectral ages have been estimated to be > 15 Myr for the oldest relativistic plasma seen in the regions close to the cores in these large sources. The spectra in the vicinity of the hotspots are somewhat steeper than theoretical expectations.

A Glimpse of the Milky Way, as may be seen by Gaia

Our view of the structure and dynamics of our Galaxy has progressed, pushed by the acquisition of ever larger datasets that encompass wider perspectives. At the dawn of the Gaia era, we are about to enter a phase of unprecedented detail in our view of our Galaxy. This opens up the possibility of using new analysis tools, or the use of traditional tools at newer scales. However, to extract the most of the Gaia database, it is necessary to immerse our theoretical models within Gaia mock catalogues to derive proper inferences about the structure of our Galaxy. In this talk we will review several tools developed by our group to construct and analyze realistic Gaia mock catalogues and some of the lessons we have learnt from them. In particular, we will present applications to the problems of characterizing the central bar of our Galaxy, the warp in the Galactic disk and identifying substructure in the stellar halo.

Formación estelar a plazos: Evidencia observacional

Se presentarán observaciones en el infrarrojo, desde 1 hasta 500 micras, describiendo las características de varias regiones de reciente, y no tan reciente, formación estelar. En muchas de ellas se encuentra un patrón recurrente en su historial: Aparecen estadíos bien definidos de "brotes" de nacimiento estelar dentro de un mismo ambiente, que en ocasiones es complejo y en otras es más simple. Normalmente, la primera generación contiene estrellas muy masivas que perturban el ambiente, dando como resultado una segunda generación con un cúmulo embebido de mediana masa, al tiempo que aparecen núcleos densos formando activamente estrellas en la actualidad.

A new, deep radio-X-ray view at the Orion Nebula Cluster

The Orion Nebula Cluster (ONC) is hosting a zoo of radio sources that has been known for decades. Additionally, the X-ray properties of its substantial YSO population have been studied in detail in the Chandra Orion Ultradeep Survey. With the advent of the newly expanded NRAO Very Large Array, we have returned to the ONC with deep simultaneous radio and X-ray observations using the VLA and Chandra. With this massive dataset, we have begun to obtain a deep census of radio sources in this region, including information on polarization and spectral indices, to systematically study YSO radio variability on time scales shorter than an hour, and to put this into the context of X-ray light curves and other source properties. Additionally, we have assembled a wealth of infrared data to assist the interpretation, including a new deep near-infrared survey (VISION) and Spitzer mid-infrared variability data obtained as part of the YSOVAR program. After presenting first results of the radio-X-ray program, I will finally discuss the prospects for radio-X-ray-IR variability studies of YSOs.

Intercambio de conocimiento en el siglo XIX.El Anuario del Observatorio Astronomico Nacional de Chapultepec (primera época)

Se presenta un trabajo que analiza el Anuario del Observatorio Astronómico Nacional de Chapultepec -primera época- en el que se manifiesta como un punto de intersección de objetivos políticos, científicos, sociales y educativos, en términos de intercambio de difusión y divulgación del conocimiento; el Anuario, también se presenta como un medio a través del cual se integraron las redes científicas locales, nacionales e internacionales con las cuales se intercambio conocimiento.

La revista, revela el papel de la cultura impresa con una imagen nítida de las practicas científicas que se desarrollaron en esa época y en las que predominan las desarrolladas por los astrónomos mas destacados del último tramo del siglo XIX (1880-1900).

El texto que se abordó desde una perspectiva socio-histórica, da cuenta de la vida social y cultural que posibilitó los avances en el campo de la astronomía, así como el papel que jugó México dentro de las comunidades científicas de la época.

Finalmente se abordará el tema de la circulación del conocimiento, en donde el Anuario también muestra su función pedagógica, dirigido a un público en general, así como a la comunidad científica que respondió a la política educativa del régimen.

The Herschel spectral surveys of star-forming regions: The interstellar shock

The key project “Chemical HErschel Surveys of Star form- ing regions” (CHESS), takes full advantage of the new opportunity offered by Herschel/HIFI and explores in a systematic way the frequency range between 480 and 1902 GHz in several star-forming regions. The goal of the project is to provide the first ever spectral census of this frequency range in a selected sample of sources covering the principal parameters and aspects of the star-formation process: mass of the forming star, its evolutionary status, and the interaction with the surroundings. In this talk I will focus on the results of the interstellar shock L1157-B1, in particular the studies of molecular species such as CO, H2O, CS, N2H+, among others.

Seminario de Doctorantes

Modelaje de la emisión de discos protoplanetarios: variabilidad IR y emisión mm

La emisión de polvo en discos protoplanetarios ocurre a distintas escalas espaciales. La región interna del disco emite preferentemente en el IR y en particular la emisión en el cercano infrarrojo proviene de la pared de sublimación, la cuál corresponde a la zona más interna dentro del disco donde el polvo aún no se ha evaporado. La emisión en el mm proviene principalmente de las regiones externas y frías del disco.

Para el primer caso presentaré un estudio de variabilidad en el cercano IR asociado a cambios en la estructura de la pared de sublimación, enfocado a 3 fuentes (LRLL 32,40 y 63) de la región jóven de formación estelar IC 348.

Para esta misma región presentaré un proyecto que se está realizando con gente de la Universidad de Massachussetts con datos del Gran Telescopio Milimétrico que arrojará información estadística de la masa de los discos.

Estructura de ionización y composición química de nebulosas Galácticas

Las estrellas masivas sufren intensos episodios de pérdida de masa a lo largo de su evolución enriqueciendo fuertemente el medio circundante. Debido a la interacción de los vientos se forman nebulosas ionizadas que condicionan cómo los nuevos metales sintetizados se dispersan y mezclan en el gas original en que se formó la estrella.

En la primera parte de la charla mostraré el estudio realizado con espectroscopía de campo integral en dos nebulosas alrededor de estrellas masivas (NGC6888 y M1-67) con el objetivo de obtener información relevante tanto de los procesos estelares internos como de la interacción de los vientos en las diferentes etapas evolutivas.

En segundo lugar describiré el trabajo realizado sobre una muestra de regiones HII del anticentro Galáctico que nos ha permitido obtener gradientes de abundancias químicas para analizar la evolución y el enriquecimiento químico de la Vía Láctea.

Active galactic nuclei observed through a set of infrared polarized eyes

The new generation of sub-arcsecond resolution infrared (IR) polarimetric instruments, CanariCam on the 10.4-m Gran Telescopio CANARIAS (GTC) and MMT-Pol on the 6.5-m MMT, have opened a new window to reveal the cores of active galactic nuclei (AGN). Using both instruments, we have been able to 1) discover a highly polarized synchrotron core in Cygnus A, 2) study the torus of NGC 1068 as a hydromagnetical outflow wind, and 3) investigate the interaction of the jet with the ionization cones in NGC 1068. This talk will introduce the polarimetric modes of CanariCam and MMT-Pol, what can be learnt from polarimetric techniques observations, and the latest results on the study of AGN using IR polarimetric techniques.

Formación de cúmulos estelares en nubes moleculares en colapso gravitacional jerárquico

High-mass star formation: from dense cores to HII regions

Establishing an evolutionary sequence for high-mass young stellar objects is one of the hot topics of current star formation. Differently to the low-mass star formation case, high-mass stars reach the zero-age main sequence while they still undergo heavy accretion, and their powerful radiation pressure should halt the infall of material, thus inhibiting growth of the stellar mass beyond 8 Msun. Recent theories, however, propose that high accretion rates and/or accretion through massive disks could overcome this problem, and explain the formation of stars with masses up to 140 Msun. In this talk I will characterize, from an observational point of view, an evolutionary scheme for the massive star formation process: which starts with dense cores with almost no (star-formation) activity, and ends with the development of HII regions that disrupt their natal cloud. I will present recent results on the physical properties of dense cores, molecular outflows, circumstellar disks, and HII regions obtained with a number of different instruments including the Atacama Large Millimeter Array.

Gas Retention and Accumulation in Dwarf Galaxies: Implications for Star Formation

The effective supply and retention of gas in shallow gravitational potentials is a problem with implications in a diverse set of astrophysical systems. In particular, the magnitude of gas flows into mature dwarf galaxies can have large impacts on the star formation histories in these systems. In this talk, computational techniques will be used to show how such such weakly bound gravitational structures might be able to accumulate gas effectively. The implications for star formation in dwarf galaxies after their incorporation into a larger host halo will be presented.

The Spreading of r-process Materia

The particular astrophysical site where r-process nuclei are synthesized remains open to more than one interpretation, being both type II supernovae and neutron-star binary mergers two likely astrophysical sites. These two mechanisms synthesized different quantities of r-process material and these differences should give rise to clear signatures in the enrichment pattern of r-process elements in galaxies and may ultimately help to constrain the dominant production mechanism. In this talk, a comparison between the propagation of the material ejected from both events will be presented. The enrichment of r-process material from these two mechanisms is analyzed in order to investigate the distribution of these nuclei along the galaxy.

Núcleos Activos de Galaxias como proveedores de material evolucionado a la galaxias anfitrionas

Los Núcleos Activos de Galaxias (AGN por sus siglas en inglés), localizados en el núcleo de alrededor de 30-40% de las galaxias observadas, generan una cantidad extremadamente grande de energía (del orden de 10^3-4 veces la energía integrada que producen las otras componentes de la galaxia). Los AGN son objetos compactos condensados en pequeñas distancias (~ 10^16-18 cm), sus masas se encuentran en el intervalo de 10^6-10^10 masas solares. En teoría, los AGN son agujeros negros súper masivos que acretan su material mas cercano. En varias galaxias con AGN se ha detectado interacción directa de materia y energía entre el núcleo y el resto de la galaxia, tal interacción podría cambiar la tasa de formación estelar de la galaxia y producir retroalimentación, debido a la mezcla de material que evolucionó en el AGN y el material de la galaxia. Ambos materiales evolucionaron en dos medios drásticamente distintos: mientras que el material del AGN evolucionó en procesos energéticos duros, el material de la galaxia evolucionó principalmente en procesos de formación estelar. En el coloquio se presentará un estudio de 5 AGN seleccionadas de una muestra de 28 galaxias con AGN tipo 1, sus espectros de rayos X muestran absorción ionizada producida por material eyectado del núcleo. El objetivo es revisar que tan plausible es el escenario donde el material ionizado del AGN alcanza el resto de la galaxia y con ello, cambie la historia de evolución de la galaxia anfitriona.

Ramas como posible evidencia de brazos espirales transitorios

Usando simulaciones MHD y de dinámica estelar, estudiamos la respuesta del disco gaseoso a dos modelos de potenciales espirales bisimétricos: una perturbación cosenoidal y el modelo PERLAS. La principal diferencia está en el número de brazos generados en el gas; mientras que el modelo cosenoidal siempre genera dos brazos gaseosos, PERLAS genera cuatro. Aunque la duplicación de brazos ha sido explicada como resultado de resonancias ultra-armónicas, estudios de órbitas periódicas nos llevan a una explicación alternativa: la formación de ramas en los brazos espirales puede ser una señal de que los brazos son transitorios.

Massive Star Formation at the Puerto Varas Workshop

The recent decades have witnessed major advances in our understanding of the formation of solar-mass stars. However, the formation mechanisms of stars at the extremes of the mass range, that is, on one hand very massive stars and on the other brown dwarfs, remain poorly understood. I will summarize the main observational results presented in a meeting on massive star formation that took place in Puerto Varas, Chile and discuss some new observational perspectives for the future.

Formación de cúmulos estelares en nubes moleculares en colapso gravitacional jerárquico

Deep into the Water Foutains

The evolution of the circumstellar envelopes of AGB and post-AGB is yet poorly understood. In particular, the mechanism(s) responsible for shaping the axisymmetric circumstellar envelopes observed towards bipolar Planetary Nebula sources remain unknown. The study of the collimated, high-velocity outflows observed towards post-AGB sources known as Water Fountain nebulae, could provide important clues about the nature of the engine shaping their circumstellar envelopes. In this colloquium I will present new results from ATCA and JVLA observations towards two representative members of the still small group of (16 confirmed up to date) Water Fountain sources.

Estudio en radio de la región de formación estelar Perseo

Radio Emission From Protostellar Jets: Some new surprising results in the last years

During the last decades protostellar jets have been intensively studied at radio wavelengths. It is now well established that young stellar objects (YSOs) in their earliest stages emit radio emission at cm wavelengths which is associated with free-free emission from the base protostellar jets. Since these objects are deeply embedded in large amounts of dust and gas surrounding the protostar, radio observations have revealed as the best way to study the phenomena that takes place very near the protostar. We have now been able to study the environment of these protostars up to physical scales of only a few AU. However, as we have performed higher sensitive and higher angular resolution observations, we have also been able to discover new phenomena which, not only, have important implications for the star formation theory, but also add new interesting questions. Here, I will talk about two important results we have obtained in two star-forming regions. The first one, the discovery of synchrotron emission from a protostellar jet, imply that protostellar jets are able to accelerate particles up to relativistic velocities, even when these objects are considered the least powerful between astrophysical jets (AGN jets, micro quasars, etc..). Moreover, the detection of linearly polarized emission allows to study the magnetic field, one of the most important ingredients in the jet formation and collimation, but yet, one of the most unknown parameters in star formation. The second results is the observation, in real time, of the collimation of a protostellar wind, posing interesting questions on how jets are collimated in these systems.

LARS: Lyman Alpha Reference Sample. Review of results

The understanding of the Lyman alpha emission (Hydrogen n:2->1) in starburst galaxies needs multi-wavelength analysis of nearby sources with high-spatial resolution. The international project Lyman Alpha Reference Sample (LARS) was defined to carry out such task. In this talk I will describe the intriguing nature of Lyman alpha emission, and the observational limitations we face. The core of the talk will be the review of the most important results obtained by LARS so far, which have led to confirm that Lyman alpha escape is a multiparametric problem.

Water fountains as seen by maser astrometry

This colloquium will focus on water fountains, huge stars with collimated and high-velocity outflows, moments before their deaths as white dwarfs enveloped in beautiful planetary nebulae. I am going to present recent astrometric results from the fastest and farthest water fountain, and through that we will discuss 1, how VLBI astrometry using maser emission helps us to study water fountains 2, the morphology of water fountain outflows 3, the variability of water maser emission and 4, how all of these tell us something about the evolutionary link between AGBs and PNe.

High redshift studies with the GTC

I will start with a brief description of the GTC, the 10.4m telescope that Mexico has access to it. The I will discuss the projects that we are undertaking using GTC data. In particular, the search for high-z Lyman α sources in the SHARDS survey. Finally I will talk about another project which aim is the study of Lymanα sources at the epoch in which re-ionization was being completed. I will show the discovery of an overdensity of sources, that will eventually become a cluster similar to or larger that the Coma cluster.

How supermassive black holes produce jets: recent insights from radio polarimetry

Substantial progress in our understanding of AGN jets has been made in recent times, particularly in relation to the conditions required for efficient jet formation, as well as our knowledge of the three-dimensional magnetic field structure of the jet. I will review our current understanding of AGN jets before presenting new radio polarization and Faraday rotation observations of radio-loud AGN from parsec to kiloparsec scales. I will show the importance of full-Stokes, broadband radio observations in providing important constraints on fundamental jet parameters such as the jet magnetic field strength, it's 3D structure, and the amount of magnetic flux at the jet launching site

A multiwavelength analysis of large surveys, what is driving the evolution of galaxies?

I will show scaling relationships between fundamental properties of galaxies such as the mass, metallicity, SFR, SSFR, and HI mass. I will introduce the GAMA survey, the Z-SSFR relation, and will talk about a model based on this relationship. Finally, using data from the SDSS, GAMA and ALFALFA surveys, we estimate oxygen yields based on the HI and metallicity measurements of a sample of ~4500 galaxies and analyze the impact of inflows and outflows in galaxies.

Galaxy formation with Molecular-regulated star formation at high redshift (z>2)

Fuentes Compactas de Radio en Regiones de Formacion Estelar Masiva

La emisión extendida de radiocontinuo en regiones de formación estelar masiva esta usualmente dominada por la emisión libre-libre de la region HII asociada. Sin embargo, cuando se observa con un interferometro de alta resolución angular, la emisión extendida se cancela y una diversidad de objetos compactos son detectados y estudiados. Estos objetos compactos incluyen a las regiones HII hipercompactas (emisión libre-libre), a las estrellas de baja masa con actividad magnetosférica (emisión girosincrotrón) y a las interfases de colisión viento-viento en sistemas binarios masivos (emisión sincrotrón). Discutimos como se pueden estudiar y caracterizar estas regiones y que información obtenemos de ellas. En particular, hay dos nuevos tipos de objetos compactos de radio cuya naturaleza no esta clara aún y que podrían revelar nuevos fenómenos.

Constraints on the Birth Environment of the Solar System

Most stars -- and hence most solar systems -- form within groups and clusters. The first objective of this talk is to explore how these star forming environments affect solar systems forming within them. The discussion starts with the dynamical evolution of young clusters with N = 100 - 3000 members. We use N-body simulations to study how evolution depends on system size and initial conditions. Multiple realizations of equivalent cases are used to build up a robust statistical description of these systems, e.g., distributions of closest approaches and radial locations. These results provide a framework from which to assess the effects of clusters on solar system formation. Distributions of radial positions are used in conjunction with UV luminosity distributions to estimate the radiation exposure of circumstellar disks. Photoevaporation models determine the efficacy of radiation in removing disk gas and compromising planet formation. The distributions of closest approaches are used in conjunction with scattering cross sections to determine probabilities for solar system disruption. The result of this work is a quantitative determination of the effects of clusters on forming solar systems. The second objective of this talk is to use these results to place constraints on the possible birth environments for our own solar system.

Cúmulos estelares jóvenes masivos: no hay formación estelar estocástica en M33

Es ampliamente aceptado que la función de distribución de las masas de los cúmulos estelares jóvenes es universal, y puede ser interpretada como una función de distribución de densidad de probabilidad con un límite de masa superior constante. Como resultado de esta visión, las masas de los objetos máas masivos estarían determinadas por el tamaño de la muestra. Por el contrario, mostramos con un alto grado de confianza que las masas de los cúmulos jóvenes (< 10 Maños) más masivos en la galaxia floculenta M 33 decrecen al aumentar el radio galactocéntrico, en contradicción con un límite superior constante de la función de masa. Además, al comparar las distribuciones radiales de densidades superficiales de gas, por un lado, y de los cúmulos más masivos, por el otro, encontramos que están correlacionadas. Por lo tanto, podemos descartar la formación estelar estocástica en M 33. El cambio en la masa máxima de los cúmulos estelares ahí debe tener causas físicas, i.e., los cúmulos muy masivos parecen requerir condiciones físicas especiales, como densidades superficiales altas de gas, para poder formarse.

La naturaleza del radio core en AGNs (Observando agujeros negros con el GTM).

La gran mayoría de fuentes extragalácticas detectadas por el satélite de rayos gamma Fermi son AGNs con jets relativistas prominentes. Estudios multi-frequencia sugieren que la producción de rayos-gamma ocurre en las partes más internas de los jets relativistas (i.e. radio core). Estas regiones no aparecen resueltas en mapas de alta resolución angular (e.g. VLBI a 7mm), lo cual complica la interpretación y modelado de los mecanismos de emisión de rayos-gamma. Sin embargo, esto está por cambiar gracias al Event Horizon Telescope (EHT) que es una red de VLBI que actualmente opera a 1mm. En esta charla se discutirán las preguntas que permanecen abiertas con respecto a la producción de altas energias en AGNs y se mostrarán ejemplos específicos en donde observaciones de super alta resolución angular con el EHT podrían restringir la región en el jet donde la radiación gamma es generada. Además, reportaremos el primer experimento de VLBI con el GTM realizado durante el verano del 2013.

Densidades, temperaturas, presiones y abundancias derivadas de líneas de recombinación del OII en regiones HII

Modelo hidrodinámico de interacción entre eyecciones de masa coronal

Las eyecciones de masa coronal (CMEs) son erupciones esporádicas de la atmósfera solar debidas a cambios en el campo magnético. El estudio de las CMEs y su interacción con otras estructuras de gran escala, es de suma importancia para entender la dinámica del plasma en el medio interplanetario y para predecir el clima espacial. En esta plática, presentaré un modelo analítico para describir la evolución de dos CMEs consecutivas que colisionan en el medio interplanetario. En este modelo, suponemos que las CMEs son perturbaciones que viajan en un medio homogéneo supersónico y superalfvénico, de tal forma que, las variaciones de la temperatura y del campo magnético son despreciables. Estas perturbaciones forman superficies de trabajo cuya evolución depende de sus parámetros iniciales como la velocidad, la densidad y su duración. Si la segunda CME viaja más rápido que la primera, las superficies de trabajo se alcanzan formando una región de presión constante cuya evolución dependerá de las condiciones iniciales de ambas superficies de trabajo. Describiré las ecuaciones y la aplicación del modelo a un evento de interacción observado el 23 de mayo del 2010. El modelo predice el arribo a 1 UA de la estructura compleja formada durante la colisión, con un error menor a una hora y 50 km/s para el tiempo y velocidad respectivamente. También presentaré algunos avances de los resultados obtenidos con una simulación numérica del mismo evento.

Título por definir

Angular Momentum and Galaxy Formation Revisited

Título por definir

Excitation of Class I Methanol Masers

Dynamics of Planetary Disks in Stellar Clusters

A VLBI Resolution of the Pleiades Distance Controversy

The Pleiades is the best studied open cluster in the sky. It is one of the primary open clusters used to define the "Zero Age Main Sequence", and hence it serves as a cornerstone for programs which use main-sequence fitting to derive distances. This role is called into question by the "Pleiades distance controversy" - the distance to the Pleiades from Hipparcos of about 120 pc is significantly different from the distance of 133 pc derived from other techniques. Although this amounts to a 10% difference in the distance, the resultant discrepancies as propagated into the Pleiades HR-diagram, and the necessary revisions of physical models to obtain agreement with the Hipparcos result, are quite significant. To resolve this issue we are carrying out a VLBI program to derive a new, independent trigonometric parallax distance to the Pleiades. We have now obtained the most accurate and precise cluster distance to date which is incompatible with the cluster distance suggested by Hipparcos.

Sinergia entre la clasificación óptica y la clasificación en rayos X de núcleos activos de galaxias

Es ampliamente aceptado que todas las familias de núcleos activos de galaxias (AGN) comparten un mismo mecanismo físico. Esto es conocido como el modelo unificado de AGNs. El componente esencial de este modelo es una estructura de polvo (simplificada como un toro) que oscurece las partes internas del AGN, impidiendo en algunas ocasiones la visión directa del mismo. Este toro es el responsable de la dicotomía entre AGNs Tipo-1 y Tipo-2. Sin embargo, este modelo unificado es incapaz de explicar todas las clases de AGN. En particular, las clasificaciones obtenidas en el óptico y en rayos X no siempre son consistentes. El objetivo de nuestro estudio es analizar la correspondencia entre las clasificaciones ópticas y los espectros de rayos X para una muestra de AGNs cercanos. Por primera vez hemos hecho este análisis sin modelar los espectros en rayos X. Esto tiene la enorme ventaja de no asumir ningún modelo físico que pueda sesgar nuestros resultados. Para ello hemos usado una red neuronal. Los resultados son: ¿Es posible que todas las galaxias contengan un núcleo activo? Más del 80% de los espectros con líneas de emisión tienen una componente de AGN, a pesar de que muchos de ellos están clasificados como no activos en el óptico. Esto significa que la fracción de AGNs en el Universo local puede ser mucho mayor de lo que se pensaba hasta ahora. ¿Se distinguen en rayos X las clases encontradas en el óptico? La mayoría de las clasificaciones ópticas muestran espectros en rayos X claramente diferenciados en promedio. Esto puede ser muy útil para surveys en rayos X (por ejemplo eRosita), donde la información óptica no está disponible puesto que nuestra red neuronal puede dar la clasificación óptica basada en la información en rayos X. ¿Es el oscurecimiento un ingrediente importante para distinguir las clases ópticas? De manera natural la red neuronal encuentra un continuo de clasificaciones entre los objetos Tipo-1 y los objetos Tipo-2 que está relacionado con el oscurecimiento de la fuente. Por tanto, el oscurecimiento aparece como uno de los ingredientes principales para agrupar las clases ópticas, tal y como predice el modelo unificado de AGNs.

Líneas satelitales del máser de OH en regiones de formación estelar

En esta plática presentaré los resultados de un rastreo de máseres de OH en regiones de formación estelar realizado con el Very Long Baseline Array. Durante este proyecto observamos 41 regiones galácticas de alta y baja masa en las frecuencias principales de 1665 y 1667 MHz, así como en las líneas satelitales de 1612 y 1720 MHz. Estas últimas raramente se encuentran en regiones de formación estelar. De las 41 fuentes de la muestra, obtuvimos observaciones de alta resolución de las líneas satelitales en 14 fuentes: cinco (11%) mostraron lineas a 1612 MHz, y diez (23%) mostraron lineas a 1720 MHz. Creemos que existe una correlación entre la presencia de líneas satelitales y las regiones de formación estelar de alta masa.

A study of the environments of giant radio galaxies using SDSS

A sample of all known giant radio sources (GRGs) has been compiled, from which a subset of sources has been selected for a detailed study of the environments of these sources by examining the distributions of galaxies in their vicinity using Sloan Digital Sky Survey (SDSS) III (DR9). We found that generally the giant radio sources do not occur in rich environments. Very few sources are in the richer environments but there is no significant signature for the asymmetric behaviour in these sources except in three giant radio sources J1021+1217, J1032+5644 and J1552+2005 (3C 326), the shorter arm is found to interact with a group of galaxies which forms part of a filamentary structure. In the case with strong and variable core, J0313+4120, the large flux density asymmetry is possibly also caused by the effects of relativistic motion.

RATIR y COATLI: Telescopios Robóticos para el Observatorio Astronómico Nacional

RATIR es un telescopio robótico que tiene desde fines de 2012 operando en el OAN/SPM. COATLI será un nuevo telescopio robótico que se pondrá en marcha en el 2016 también en el OAN/SPM. Ambos tienen capacidades científicas únicas. RATIR permite realizar fotometría multibanda de objetos variables durante meses y años. COATLI permite obtener imágenes con una resolución de alrededor de 0.3 segundos de arco y con una cobertura amplia en el cielo. Los proyectos muestran que instrumentos innovadores permiten ciencia de punta.

Propuestas para la investigación científica en en México

Fricción Gravitacional de Sistemas Binarios en Medios Gaseosos

La fricción gravitacional se define como la fuerza de frenado que siente un objeto masivo (perturbador) moviéndose a través de un medio de fondo, esto es, debido a la interacción gravitacional de este objeto con su estela inducida en el medio de fondo. Utilizando la teoría lineal de perturbaciones y un método semianalítico, evaluamos la fuerza de fricción gravitacional de un sistema binario suponiendo que su centro de masa se desplaza a velocidad constante en un medio gaseoso de densidad uniforme. Considerando además la velocidad de rotación de cada componente del sistema binario alrededor del centro de masas. Este trabajo es una generalización de lo realizado por Ostriker en 1999, quien derivó la expresiones analíticas para la densidad de la estela y la fuerza de fricción cuando el perturbador se mueve a velocidad constante en un medio gaseoso, y Kim y Kim en 2007, quienes evaluaron la fuerza de fricción cuando el perturbador se mueve en una órbita circular en un medio gaseoso. Obtuvimos la densidad de la estela que se genera y, conocida la densidad, se evaluó la fuerza de fricción dinámica numéricamente.

The Shock-Induced Star Formation Sequence Resulting from a Constant Spiral Pattern Speed

We utilize a suite of multiwavelength data, of 9 nearby spirals, to analyze the shock-induced star formation sequence, that may result from a constant spiral pattern speed. The sequence involves tracers as the HI, CO, 24um, and FUV, where the spiral arms were analyzed with Fourier techniques in order to obtain their azimuthal phases as a function of radius. It was found that only two of the objects, NGC 628 and NGC 5194, present coherent phases resembling the theoretical expectations, as indicated by the phase shifts of CO-24um. It was also found that the phase shifts are different for the two spiral arms. With the exception on NGC 3627, a two-dimensional Fourier analysis showed that the rest of the objects do not exhibit bi-symmetric spiral structures of stellar mass, i.e., grand design spirals. A phase order inversion indicates a corotation radius of ~95'' for NGC 628, and ~189'' for NGC 5194. For these two objects, the CO-Halpha phase shifts corroborate the CO-24um azimuthal offsets. Also for M51, the CO-70um, CO-140um, and CO-250um phase shifts indicate a corotation region.

Chaotic Dynamics of Halley's Comet: Lyapunov Exponent and Survival Time Prospect

We have explored the dynamical evolution of the comet 1P/Halley over 1 Myr with detailed numerical simulations, under the gravitational influence of all planets in the present day Solar System (except Mercury). To this purpose we employed the Mercury 6.2 code, including, in addition to the planets, the 9 biggest minor bodies (among them the known as dwarf planets but Sedna) to conduct the N-body simulation. Halley ́s comet fiduciary orbit, and a set of orbits surrounding it in phase-space (a-e), are solved as test particles in this problem. The ensemble of orbits explored is constructed as a mesh of 10,000 particles with different initial conditions covering the observational error of Halley’s orbit in semimajor axis and eccentricity (+- 10-6 AU and +- 10-6, respectively). We find that the comet’s fate is highly sensitive on initial conditions. Survival time maps from the simulations and Laskar frequency analysis maps for the vicinity of Halley’s comet are shown. Also, the maximum Lyapunov exponent for neighboring orbits is calculated. This shows that chaos is dominant for these highly eccentric bodies as found by Chirikov & Vecheslavov (1989) and produces large non-stable regions for the comet ́s surrounding phase space. We provide estimations of the probability of survival of the Halley ́s comet and a general perspective about the dynamical evolution of comets on a wider region of phase-space which covers several currently known Halley type comets.

Un tutorial relámpago de Estadística Bayesiana para Astrónomos (o, lo que siempre quiso saber sobre el tema pero temió estudiar por su cuenta)

El uso de la Estadística o Inferencia Bayesiana es cada vez más frecuente en diversas áreas de la astrofísica. Aún así, éste es un tópico que no suele ser incluido como parte de la formación de estudiantes de perorado y posgrado en física y astronomía. En esta charla expondré las bases del formalismo Bayesiano mediante su aplicación a un conjunto de problemas simples y fundamentales, útiles en diversas áreas de la astronomía. Enfatizaremos las ventajas que la Inferencia Bayesiana ofrece en el cálculo e interpretación de la probabilidad, en contraste con los métodos clásicos de la estadística frecuentista.

Observing in 'real time' the transition from a non-collimated outflow into a jet outflow in a massive YSO

There is growing evidence provided by VLBI water maser observations suggesting that at the earliest stages of evolution of massive YSOsthere may exist short-lived (tens of years) episodic events associated with very poorly collimated outflows. This result is surprising since the current paradigm of star formation through accretion disks, and gas ejection via MHD mechanisms, does not predict outflows expanding without any preferential direction, but producing collimated outflows. From all the observed cases, the most singular is the one found in the high-mass star-forming region of W75N(B). In fact, in 1996, we detected a water maser shell of 0.1'' (130 AU) diameter around an unresolved (<0.1'') radio continuum source (VLA2). Monitoring this shell from 1996 to 2012, we find that it is expanding at ~ 30 km/s and, more importantly, that it has evolved from an almost circular shock-excited shell to an elliptical morphology of 0.28''x0.14'' size with a kinematic age of ~ 25 yr. In addition, the magnetic field around VLA2 seems to have also changed its orientation according to the new direction of the major axis of the shell. All these observations suggest that we are observing in "real time'’ the transition from a non-collimated, pulsed outflow event into a jet-like mass outflow during the first stages of evolution of a massive YSO. In this talk we will present all these results that could represent a major breakthrough in our knowledge of the formation and evolution of massive YSOs. We predict that VLA2 itself should have also evolved from a compact radio continuum source up to an elongated source, and with a spectral index consistent with a thermal radio jet. Very preliminary results of very recent (2014) sensitive and high angular resolution VLA observations of the radio continuum emission of VLA 2 will be briefly presented (Carrasco-Gonzalez et al. 2014). Possible scenarios to explain the origin of the initial non-collimated outflow are considered, although the origin of the transformation into a jet-outflow is still under study.

Formation and evolution of cores in globally collapsing environments

I will present recent results on the hierarchical gravitational fragmentation (HGF) of molecular clouds (MCs) leading to the formation of dense cores. I will first discuss the scenario of HGF as an alternative to the standard scenario of turbulent support --> turbulent dissipation --> collapse. In it, clouds are multi-Jeans-mass object undergoing global, multi-scale collapse, and the cores are the local centers of collapse. The lapse between the onset of local collapse and the formation of a singularity constitutes the prestellar phase. I will present numerical simulations of core growth during this phase in the idealized case of spherical geometry, immersed in a globally collapsing environment, discussing the evolution of the density and velocity profiles. I will also present synthetic molecular line observations of such idealized cores, aimed at determining to what extent such an idealized setup recovers the basic observational features of the cores, and which features require additional physics such as background turbulence and non-spherical symmetry.

T.B.D.

Evolución de AGNs en simulaciones cosmológicas

En esta plática voy a presentar la evolución de núcleos activos de galaxias (siglas en Inglés AGNs) en simulaciones cosmológicas. En particular, voy a hablar de simulaciones hidrodinámicas modernas diseñadas para producir un Universo virtual que reproduce las propiedades observadas de una población de galaxias, tal como la función de masa estelar de galaxias a z=0. La simulación engloba una región de 100 Mpc, resolviendo la formación de galaxias individuales con una resolución de 700 pc. La energía de feedback injectada por los agujeros negros es una parte clave de la simulación la cuál me enfocaré en esta plática. También mostraré la evolución de la función de luminosidad de los AGNs en bandas de rayos X así como otros resultados de la población de AGNs.

The complex dust formation zone of the AGB star IRC+10216 probed with CARMA 0.25'' angular resolution molecular observations

The Asymptotic Giant Branch stars (AGB) are evolved solar-type stars surrounded by a circumstellar envelope (CSE) composed of molecular gas and dust. The processed matter that gives rise to the CSE is expelled from the star towards the Interstellar Medium due to the stellar pulsation and accelerated by the pressure of stellar radiation on the dust grains. During most of the AGB phase, the envelope is considered spherically symmetric at large scales. However, there could be asymmetries at small scales probably related to the development at the end of this stage of the bipolar outflows observed in the proto-planetary nebulae. Hence, the observation and analysis of these asymmetries could throw some light on the formation of the outflows. IRC+10216 is one of the best known C-rich AGB stars because of its proximity (~120 pc) and chemical richness. This star, usually considered the archetypical AGB star, has developed a CSE with a dusty component elongated along the NE-SW direction in the plane of the sky. This elongation was observed at scales of 0.1-0.2" and 1" in the near- and mid-IR (e.g., Ridgway & Keady, 1988; Weigelt et al., 1998) evidencing the presence of a bipolar structure close to the central star. Regarding the molecular emission, only the brightness distributions of SiC2 and CN are elongated along the NE-SW and the perpendicular direction at scales of 20-40" while the emission of other molecules such as SiS, HCN, CS, HC3N, C3N is roughly spherically symmetric (Takano et al., 1992; Bieging & Tafalla, 1993; Gensheimer et al. 1995; Lucas et al., 1995). However, the molecular observations at scales smaller than 0.6" are very scarce and no molecular counterpart of the bipolar structure in the dusty component of the envelope has been found so far. In this talk, we will present new low spectral, high angular resolution molecular observations (HPBW>0.25") of SiS, H13CN, SiO, and SiC2 carried out with CARMA at 1.2 mm. These observations are analyzed in detail with a new version of the code developed by Fonfría et al. (2008) to model the continuum and molecular emission of spherically symmetric envelopes, improved to reproduce the 3D emission of asymmetric envelopes. The derived abundance distribution of H13CN, SiO, and SiC2 suggests the existence of three remarkable directions towards the NE, SSW, and SE between the stellar surface and ~50R* (~1") along which the abundance of these molecules (and the vibrational temperature in the case of SiO) are clearly different than for other directions in the plane of the sky. The SiS observations cannot be used to analyze these remarkable directions but they support the existence of maser emission in the observed line (v=0, J=14-13) proposed by Fonfría et al. (2006) and allow us to sketch the maser emitting structure located in the innermost envelope.

Ni los veo, ni los oigo': The radio signal of protoplanetary disk photoevaporation is faint

The gas in protoplanetary disks has to be dispersed to give rise to planetary systems. The final dispersion mechanisms remain debated. Photoevaporation by high-energy photons and the growth of planets itself are among the main candidates. In this talk, I will describe a result from an spin-off project of our young stellar object time monitoring campaign. Using our deeper radio images, we constrain some of the basic inputs of models of the dispersal of protoplanetary disks by photoevaporation. In particular, we set stringent upper limits to the extreme-UV photon luminosity, Phi_EUV < 1 to 4 x 10^41 s^-1, which lie at the lower end of what models need. Our results suggest that EUV photoevaporation likely is not the main agent in disk dispersal. Multiwavelength observations, including deeper radio images, can confirm this and test photoevaporation by X-rays.

Procesos de formación estelar y emisión de altas energías en galaxias 'starburst' y Seyfert 2

En este seminario haré un breve resumen de una parte de mi actividad científica hasta la fecha. Aquélla comprende:

• Calibración de estimadores de formación estelar usando modelos evolutivos de síntesis de población
• Análisis de los estallidos de formación estelar en dos galaxias "starburst" locales emisoras de Lyman alfa
• Emisión de rayos X de alta energía en galaxias "starburst"
• Discernimiento de la formación estelar de la actividad nuclear en galaxias Seyfert 2 usando espectroscopía de rayos X

A multifrequency study of spectral and structural asymmetries in three large radio galaxie

We present the results of multifrequency observations of three large and asymmetric radio sources with the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). The radio luminosity of these sources are in the Fanaroff-Riley class II (FRII) range. These sources have diffuse lobes of emission, reminiscent of FRI radio sources, on one side of the galaxy although the opposite lobe has a hot-spot or peak of emission. We suggest the peak brightness asymmetries to be largely intrinsic in these Mpc-scale sources. Unlike in the case of lobes with hot-spots, the spectral index of the diffuse lobes remains largely similar with distance from the edge of the lobe, possibly due to reacceleration of particles in these diffuse lobes. This trend also suggests an intrinsic asymmetry in the lobes, rather than the hot-spots being invisible due to relativistic beaming effects. We also discuss the core radio spectra of these sources.

Formation of cold clouds and their substructure

I will review recent theoretical work on the formation cold atomic and molecular clouds and their substructures -- filaments and dense clumps. At least under Solar Circle conditions, the convergence of large-scale gas streams in the diffuse medium, caused by either turbulent motions or larger-scale instabilities, may coherently trigger the production of large extents of cold gas through thermal instability. The clouds may thus quickly acquire masses much larger than their thermal Jeans mass, engaging in large-scale, nearly pressureless, gravitational contraction. Under these conditions, collapse proceeds along the shortest dimension first, sequentially forming filaments and then clumps. Gravitationally-formed filaments grow in mass until they become locally unstable, forming the clumps. The remainders of the filaments then accrete onto the clumps, because an elongated structure has a longer free-fall time than a spherical one. I review the basic analytic theoretical results concerning the radial structure of filamentary structures in hydrostatic equilibrium, and extensions to collapsing and accreting cases.

The clumps themselves grow in mass in such a way that their early, pre-stellar stages resemble Bonnor-Ebert spheres. Clumps formed by this mechanism appear nearly virialized, but the nonthermal motions in this case do not represent true turbulent, random motions, but instead are dominated by infall, superposed on a moderately turbulent background. Clumps appearing as "unbound" of "pressure-confined" may actually be the result of an underestimation of the relevant gravitational mass.

In this scenario, a low star formation efficiency can be maintained because stellar feedback is capable of shutting off local star formation events after roughly 10% of the local gas mass has been converted into stars, at least for low- to intermediate-mass clouds. To conclude, I will by briefly compare this scenario with the alternative view of clouds in approximate virial equilibrium, controlled by supersonic turbulence.

Gravity or turbulence: does turbulence control core fragmentation and dynamics?

I will present an observational project aimed at studying the fragmentation of massive dense cores, which constitute the first stages of cluster formation and the cradles where high-mass stars are born. The project is based on a sample of 19 protoclusters with luminosities spanning three orders of magnitude, and which were observed in the millimeter range down to mass sensitivities (~0.3 Msun) and spatial resolutions (~1000 AU) comparable to infrared/optical studies of clusters. Among the 19 regions, 30% show no signs of fragmentation, while 50% split up into >~ 4 millimeter sources. We inferred the density structure of the 19 cores through a simultaneous fit of the submillimeter radial intensity profiles and the spectral energy distribution, and find a possible trend of fragmentation increasing with density within a given radius. We also studied the relation between turbulence and fragmentation level and find that gravity, rather than turbulence, seems to be a key ingredient in determining the fragmentation level of massive dense cores. Finally, I will present independent very recent results of different fragmentation levels in two massive cores of the infrared dark cloud G14.225−0.506, which again suggest that gravity is regulating the fragmentation process in this cloud.

Formation of magnetized accretion disks around young stars

The formation of a rotationally supported disk is a crucial event of star formation, both currently and likely in the early Universe. This circumstellar disk is the place where planets form. I would like to draw attention to a fundamental difficulty with circumstellar disk formation in the presence of magnetic fields, and review possible solutions of this difficulty based on state of the art numerical simulations.

It had been expected that a disk would form automatically out of the collapse of rotating cores because of angular momentum conservation. However, this simple explanation is not guaranteed to work, because magnetic braking and magnetic instabilities can oppose disk formation, in the presence of the observed level of magnetic fields in star-forming regions of our local universe. Indeed, in the simplest case of ideal MHD in axisymmetry, analytic and numerical work showed that disk formation is completely suppressed by excessive magnetic braking of rotation --- leaving insufficient angular momentum to form a disk.

Nevertheless, protostellar disks are commonly observed, and some of them are large. Based on our numerical simulation work, I will discuss in particular three of the suggested resolutions of this problem: diffusion, asymmetry, and turbulent waves.

Direct magnetic diffusion, such as Ohmic dissipation and the Hall effect, needs to reach very large values to be able to form large disks. Enhanced diffusive effects such as turbulent reconnection diffusion can be of great help in decoupling mass from magnetic flux.

Both turbulence (in the form of waves) and asymmetry (in the form of misalignment between magnetic field and rotation) have been shown to form strongly warped, highly asymmetric infalling structures feeding the disk with matter and angular momentum. In our simulations, this warping helps to decouple mass from magnetic flux, and it also decreases the angular momentum removal due to magnetic torques and magnetized outflows. Together, both beneficial effects of warping enable the formation of a rotationally supported disk.

The Cold Phase of Kinetic Black Hole Feedback

LCDM Cosmology at further smaller scales: Milky Way and SMBH's

In this presentation I will discuss a relatively unexplored connection between LCDM structure formation scenario and the evolution of binary supermassive black holes, and how this connection can be exploited in observations and theory. I will also review the value of selfconsistently producing the formation of a Mily Way like galaxy system inside a cosmological galaxy formation simulation. I will present one of the newest efforts designed to be a laboratory for galactic astronomy and its potential for constraining the history of MW Super Massive Black Hole.

Servicio de Clima Espacial-Mexico (SCIESMEX) / proyecto de cátedras de CONACYT / Inst. Geofisica, Unidad Michoacan (IGUM)

Se presenta el proyecto del Servicio de Clima Espacial-Mexico (SCIESMEX). El SCIESMEX es un proyecto aprobado por la convocatoria de Cátedras de Jóvenes investigadores de CONACyT para desarrollarse en la Unidad Michoacán del IGEF (IGUM). Se explica la motivación: ¿qué es el clima espacial? ¿por qué necesitamos estudiar el clima espacial en México? ¿qué dice la nueva ley de protección civil? ¿cuál es el contexto nacional e internacional del proyecto? ¿cómo se relaciona con el plan de desarrollo del IGEF y de la Agencia Espacial Mexicana (AEM)? El SCIESMEX forma parte de los servicios geofísicos que brinda el IGEF a la nación (SSN, SMN, Servicio Magnético), y va a operar dentro una coordinación internacional de servicios de clima espacial (ISES), conformandose como un 'Warning Regional Center' (WRC) del ISES. Vamos a explicar la operación y fortalecimiento de la red de instrumentos de clima espacial de la UNAM, la adquisición, resguardo y acceso de sus datos, retomando el proyecto del VESO para hacerlo un verdadero observatorio virtual (Repositorio Nacional de Datos de Clima Espacial). Explicaremos también cómo funciona el servidor del SCIESMEX y su operación en redes sociales, como una aplicación de datos de clima espacial en tiempo real, responsable de emitir las alertas regionales de eventos solares potencialmente riesgosos en términos de clima espacial. Finalmente anunciaremos e invitaremos a la conferencia de clima espacial y observaciones remotas de la heliosfera interna que se va a desarrollar en Morelia en octubre de 2015.

Título por definir

A story of some molecules in Astrophysics

After a quick reminder of the history of detecting molecules in space and of the main channels of molecule formation I will select a few examples to demonstrate the use of the cosmic chemical laboratory in determining basic properties of matter that could not be obtained otherwise, and of some applications to the processes of star formation. Special attention will be given to the water molecule, both to its physics and its appearance in space. Then the astro search for ever larger molecules will be discussed with a view on the presence and origin of prebiotic cosmic substances such as the ones recently discovered at the Max Planck Institute of Radio Astronomy in Bonn.