Found 55 talks width keyword galactic formation

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/

Youtube933518

Within the hierarchical framework for galaxy formation, merging and
tidal interactions are expected to shape large galaxies up to the
present day. While major mergers are quite rare at present, minor
mergers and satellite disruptions - that result in stellar streams -
should be common, and are indeed seen in the stellar halos of the Milky
Way and the Andromeda galaxy. In the last years, the Stellar Stream
Legacy Survey (PI. Martinez-Delgado) has exploited available deep
imaging of some nearby spiral galaxies with the ultimate aim of
estimating the frequency, morphology and stellar luminosity/mass
distribution of these structures in the local Universe. In this talk, I
will present the first results of our systematic survey of stellar
streams together with some recent follow-up observations (e.g. Megara,
Subaru) and N-body modelling of the most striking streams. Finally,
I will discuss what we can learn about galaxy formation from the results
of this survey, including the comparison with the available L-CDM
cosmological simulations, and our plans to extend this stream survey
at lower surface brightness regime with the recently approved ARRAKHIS,
the first ESA fast-mission lead by Spain.

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.

The formation of the first galaxies in the Universe is the new frontier of both galaxy formation and reionization studies. In fact, we will soon directly observe primeval galaxies thanks to the James Webb Space Telescope, and witness the reionization process through 21cm intensity mapping experiments. This unique moment in human history creates a fierce new challenge, i.e. to simultaneously understand in a unique and coherent picture the processes of galaxy formation and reionization, and – crucially – their connection. The latter, in particular, has escaped past numerical efforts. In this talk I will present the first results on this front from an years-long effort geared toward achieving such comprehensive picture, culminated in the Thesan suite of cosmological radiation-magneto-hydrodynamical simulations. I will briefly introduce the features of Thesan, highlighting the successes and failures of its physical model. Thesan produces realistic galaxy populations thanks to state-of-the-art physics, including self-consistent dust production+destruction and radiation transport. I will then show how Thesan can, for the first time, reproduce the connection between IGM and galaxies, as measured from the modulation of the Lyman-alpha flux around galaxies. Finally, I will chart the way forward towards and even deeper understanding of the emergence of the first structures in the Universe.

Recent years have seen impressive development in cosmological simulations for spiral disc galaxies like the Milky Way. I present a suite of high-resolution magneto-hydrodynamic simulations that include many physical processes relevant for galaxy formation, including star formation, stellar evolution and feedback, active galactic nuclei and magnetic fields. I will discuss how these processes affect the formation of galactic discs, and what these simulations can tell us about the formation of the Milky Way, such as the properties of the Galaxy's putative last significant merger and its effect on the formation of the thick disc and stellar halo. 

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.

Bosonic ultra-light dark matter (ULDM) in the mass range m ~ $10^{-22} - 10^{-21} \rm eV$ has been invoked as a motivated candidate with new input for the small-scale `puzzles' of cold dark matter. Numerical simulations show that these models form cored density distributions at the center of galaxies ('solitons'). These works also found an empirical scaling relation between the mass of the large-scale host halo and the mass of the central soliton. We show that this relation predicts that the peak circular velocity of the outskirts of the galaxy should approximately repeat itself in the central region. Contrasting this prediction to the measured rotation curves of well-resolved near-by galaxies, we show that ULDM in the mass range m ~ $10^{-22} - 10^{-21} \rm eV$ is in tension with the data.