Found 14 talks width keyword stellar content
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/
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.
Vimos Public Extragalactic Redshift Survey (VIPERS) is a spectroscopic survey designed to investigate the spatial distribution of ~90k galaxies on redshift 0.4<z<1.2. The catalogue of spectroscopic observations, combined with auxiliary photometric data, is perfect for evolutionary studies of different types of galaxies. But also for tracing rare objects. One of them are the so-called “red nuggets”, progenitors of the most massive galaxies in the local Universe. The discovery of red nuggets - highly massive, passive and extremely compact galaxies - at high redshift challenged the leading cosmological models, as they do not fit into the evolutionary paths of passive galaxies. Taking into account that the galaxies' mergers are stochastic events, it is possible that some red nuggets remain relatively unaltered for billions of years. Those survivors constitute a group of unique galaxies in the local Universe, commonly named “relics”. Despite numerous studies dedicated to red nuggets and relics, the link between the population of compact, massive, passive galaxies in the early Universe and their remnants in the local Universe, is still poorly understood.
In my talk I will present the first spectroscopically selected catalogue of red nuggets at the intermediate redshift. It is the most extensive catalogue of this kind of galaxies above redshift z > 0.5. Selected under the most strict criteria, the group of 77 objects consists of a statistically important sample, which allows for analysis of physical properties of those rare passive giants. I will discuss the influence of compactness criteria on the sample size. Moreover I will present VIPERS red nuggets number densities and discuss the environmental preferences of those exceptional galaxies.
In the local universe most of the stellar mass is in passive galaxies, where star formation is
absent or at very low levels. Understanding what are the mechanisms that have been
responsible for quenching star formation in galaxies, and transforming them into passive,
quiescent systems, is one of the main observational and theoretical challenges of extragalactic
astrophysics. I will give a brief overview of the several possible quenching causes and physical
processes that have been proposed so far, ranging from feedback from black hole accretion and
starburst activity, to effects associated with the large scale environment in which galaxies live.
Although most of these mechanisms and causes play a role in different classes of galaxies and
at different epochs, multi-band observations are providing growing evidences that just a few of
them play the key, dominant role.
I will conclude by providing prospects for further investigating these aspects and tackling open
questions with the next generation of observing facilities.
Stellar population synthesis has reached a high degree of sophistication that has been exploited to understand to a certain extent the mechanisms of formation, assembling, and evolution of galaxies in our universe. Progress is based on solid results in the field of stellar evolution and spectrophotometric observations of large numbers of stars and galaxies. However, there are certain phases of stellar evolution, like the thermally pulsing asymptotic giant branch (TP-AGB) phase, the Wolf-Rayet stage, and the presence of interacting binaries, whose treatment is either ignored or extremely simplified in galaxy evolution models due to the uncertainties in their description. In this talk I will present results from models that add the state of the art in the treatment of these evolutionary phases to traditional population synthesis models.
The nearby spiral galaxy M81 contains a population of 3 kinds of stellar clusters - super star clusters, globular clusters and fuzzy clusters. Over the past few years, we have taken GTC longslit spectra of around 20 of these clusters, with the intention of obtaining their spectroscopic ages. These spectra have allowed us to understand the nature of the brightest globular cluster in this galaxy. In addition, we were able to address the problem of the origin of the fuzzy clusters. In the talk, I will summarize the results we have obtained so far.
Based on the double exponential behaviour of the gas mass profile and on the O/H gradient, Robles-Valdez, Carigi & Peimbert (2013) built a sucessful chemical evolution model for M33. The model predicts that in the inner parts of M33 the star formation history follows an inside-out scenario, like M31 or the MW, but in the outer parts of M33 the star formation history follows an outside-in scenario, as dwarf galaxies of the Local Group.
The general picture of galaxy formation and evolution includes bars as the main drivers of the internal secular processes affecting the lifetime of disc galaxies. Bars are present in a very high fraction of all the spiral galaxies found at different redshifts, and the processes inducing their formation or the effects they may have on their host galaxies are still under discussion. Particularly interesting is the case of double-barred galaxies: at least 20% of all spirals have turned out to host not only one but two bars embedded in them. These two bars appear randomly oriented and independently rotating. The formation of such a double-barred system has been the goal of several numerical simulations and the results obtained so far can be roughly divided in two big groups: gas-rich and gas-free formation scenarios. In the same way a single bar does, double-bar systems might also promote gas inflow and contribute to the internal secular evolution. Moreover, they have also been proposed as a very efficient mechanism for the feeding of the active galactic nuclei.
All the previous theoretical hypothesis on the formation and evolution of double-barred galaxies have not been tested due to the lack of observational works focused on these systems. With this motivation, during my PhD I observed a sample of double-barred galaxies in order to fully analyse their kinematics and stellar populations. Among the most interesting results, it is important to highlight the discovery of the sigma-hollows, which are the only known kinematical signature of the presence of inner bars, or the fact that inner bars are younger and more metal-rich than their surrounding regions. In this talk I will present the whole work and discuss the results in the framework of the different formation scenarios and the role that these inner bars may be playing in the evolution of their host galaxies.
In recent years accurate photometric and spectroscopic observations have
provided sound evidence that Galactic Globular Clusters can not be longer
considered the prototype of Simple Stellar Populations. In this talk we
present the most recent updates concerning the empirical evidence and
discuss the theoretical framework required for interpreting observations.
Current shortcomings in the interpretation of how the multiple stellar
populations formed in a given cluster are also discussed.
Disks in spiral galaxies consist of stars and gas. The stellar disks show radially an exponential surface brightness distribution (and vertically one resembling an isothermal sheet), with relatively sharp truncations at of order 4 scalelengths. These truncations are most easily seen in edge-on galaxies. The evidence for these truncations and their statistics will be reviewed. Truncations appear to be not only truncations in the distribution of stars, but also in the total density. The origin of these truncations seem related to the maximum specific angular momentum in the material that formed the disks. Disks are extremely flat. The HI-gas often extends beyond the eructations in the stellar disks, but when they do they also show a warp. Again edge-on galaxies show this mostly readily. Analysis shows that the warps start abruptly, just beyond the truncation radius and some other properties also show abrupt changes at the radius of the onset of the warp. This suggests that warps are the result of infall of gas at later times, when the formation of the stellar disks has been completed. The open issue is still that we have not conclusively shown that we can discover the face-on analogs of the truncations we see in edge-on disk. I will outline some recent research I have been involved in and some ideas for further work and collaborations.
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- 2022 Nobel Prize and the Challenges of Bell's Inequality: Closing the Freedom of Choice LoopholeDr. Amin BabazabehThursday November 30, 2023 - 10:30 GMT (Aula)
- TBDThursday December 14, 2023 - 10:30 GMT (Aula)