Found 220 talks archived in Galaxies

The massive globular cluster Omega Centauri is likely the stripped nucleus of an accreted dwarf galaxy and, therefore, provides a unique opportunity to study the central region of a galaxy, whose evolution halted billions of years ago.

In the last years we have created oMEGACat, the largest astrometric and spectroscopic dataset for any star cluster, with the goal to decipher both the formation history and the dynamics of Omega Centauri.

I will give an overview of this project and then focus on the exciting discovery of several fast-moving stars in the very center of the cluster. These stars provide the potentially best evidence for an intermediate-mass black hole (IMBH) we have to date.

 These elusive IMBHs have masses between the stellar mass black holes and supermassive black holes and may provide a missing link in our understanding of the formation of super-massive black holes

Nebular emission lines are a powerful diagnostic tool for tracing the chemical evolution in star-forming galaxies (SFGs) across cosmic time. Due to their proximity, SGFs are ideal for studying the physical properties, stellar population, and nebular gas in much more detail. The COS Legacy Spectroscopy SurveY (CLASSY) is a treasury survey that comprises UV+optical spectra of 45 local SFGs covering a broad range of physical properties. In this talk, I present the results of the physical conditions and metallicities for the CLASSY sample focused on the impact of the aperture effects of the inferred metallicities and the abundance patterns of several elements. We found that the results for the inferred electron density, temperature, and metallicity derived using different aperture sizes, 1″-3″, are consistent, indicating a uniform mapping of the nebular gas. We also showed that the physical properties derived from the optical are appropriate for observations in the far-UV, allowing a better interpretation of the interplay between the stellar and gas components. I will also discuss the results of the Ne/O, Cl/O, S/O, and Ar/O vs. O/H relations and their behaviour with different galaxy properties (e.g., stellar mass and star formation rate). We found that such abundance ratios follow a constant trend with O/H as expected, except for Ne/O and Ar/O, which show a significant trend at high metallicities. We discuss the scatter involved in the N/O versus O/H relation and its connection with the different UV+optical observables. Finally, we compare these results with the chemical abundances derived at z > 6 galaxies observed with the JWST.

Using CGMS deep integral field data we have discovered that the massive galaxy NGC 1277 has no dark matter. This is the first time that a galaxy as massive as the Milky Way or more is found to be dark matter deficient. This result is unexpected within the Lambda-CDM cosmological paradigm. We propose several alternatives to explain this intriguing observation but none is completely satisfactory, so the mystery about how to generate a galaxy without dark matter remains.

Zoom: https://rediris.zoom.us/j/81895121297?pwd=YnVpaTdUVkZvN25RYmkrN2VOV3pEdz09

ID: 818 9512 1297

Passcode: 460746

Youtube: https://youtube.com/live/TMctBBbLn9Y?feature=share

We present the extended data release of the Calar Alto Legacy Integral Field Area (CALIFA) survey (eDR). It comprises science-grade quality data for 895 galaxies obtained with the PMAS/PPak instrument at the 3.5 m telescope at the Calar Alto Observatory along the last 12 years, using the V500 setup (3700-7500Å, 6Å/FWHM) and the CALIFA observing strategy. It includes galaxies of any morphological type, star-formation stage, a wide range of stellar masses ( ∼10^7-10^12 Msun), at an average redshift of  ∼0.015 (90\% within 0.005 < z <0.05). Primarily selected based on the projected size and apparent magnitude, we demonstrate that it can be volume corrected resulting in a statistically limited but representative sample of the population of galaxies in the nearby Universe. All the data were homogeneously re-reduced, introducing a set of modifications to the previous reduction. The most relevant is the development and implementation of a new cube-reconstruction algorithm that provides an (almost) seeing-limited spatial resolution (FWHM PSF  ∼1.0").  Furthermore we present the analysis performed using the pyPipe3D pipeline for these dataset. We include a description of (i) the analysis performed by the pipeline, (ii) the adopted datamodel for the derived spatially resolved properties and (iii) the catalog of integrated, characteristics and slope of the radial gradients for a set of observational and physical parameters derived for each galaxy. All these data has been distributed through the following webpage: http://ifs.astroscu.unam.mx/CALIFA_WEB/public_html/

Finally, I will summarise our ongoing JWST work within the GATOS (Galactic Activity, Torus and Outflow Survey) collaboration. In particular, I will focus on our recent study about the survival of PAH molecules in AGN-driven outflows.

Youtube933518

I present a detailed analysis of the scaling relations of ETGs and suggest a way to predict the evolution of the distributions of galaxies in these planes. This new approach is able to account of several features observed in the FP projections and of the tilt of the Fundamental Plane.

Dwarf galaxies are powerful tools of near-field cosmology and galactic archaeology: their numbers, distribution, and star formation can be linked to both the tenets of LCDM (the missing satellite "problem," their (an)isotropic distribution, their dark matter content) and to the build up of their hosts and their environment (accretion, quenching). The exquisite detail offered by observation of the nearby Milky Way dwarf galaxies has built a picture of what dwarf galaxies are and how they evolved through time. In this talk, I will review the increasingly sharp view we are building of the dwarf-galaxy system of the Milky Way's "sister" galaxy, Andromeda, and emphasize key similarities and differences between these two systems of satellites in the hope to learn what features are common or, on the contrary, driven by the different pasts of the Milky Way and Andromeda.

In this talk, I will present recent results on a new sample of extremely UV-luminous star-forming galaxies at z=2-4 discovered within the 9000deg^2-wide Baryon Oscillation Spectroscopic Survey database of the Sloan Digital Sky Survey. These puzzling sources show apparent magnitudes rivaling those of bright QSOs, but without any hint of AGN activity or being magnified by gravitational lensing. Instead, these sources are characterized by very young stellar populations (~ 10 Myr) and compact morphologies. The two highest-redshift sources in our sample show very high Lyman continuum (LyC, with >13.6 eV) escape fractions, up to fesc(LyC)~90%, being the most powerful ionizing sources identified so far among the star-forming galaxy population, both in terms of the intrinsic LyC photon production rate and escape. With SFRs~1000 Msun/yr, but almost un-obscured, and specific star formation sSFR >50-100 Gyr^-1, these sources are very efficient star-forming galaxies, possibly representing a short-lived phase in the evolution of massive and compact galaxies. I will highlight some unique properties observed in these sources including LyC emission, complex Lyman-alpha profiles, strong wind lines, SEDs, among others. Finally, I discuss the properties of these UV-bright sources in the broad context of galaxy formation and evolution, and possible implications to cosmic reionization.