Found 9 talks width keyword Morphologies

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Thursday December 2, 2021
Prof. Roberto Maiolino
Kavli Cambridge

Abstract

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.


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Thursday May 27, 2021
Dr. Manuela Bischetti
INAF/Trieste

Abstract

This talk will be dedicated to luminous (LBol~1E47 erg/s),
high-redshift quasars, which are ideal targets to investigate (i) feedback
from SMBHs, and (ii) the early growth phases of giant galaxies. I will
present evidence of  SMBH-driven outflows  at all Cosmic epochs, back to
the early Universe. These outflows involve all gas phases (molecular,
neutral, ionised) and extend on nuclear to galactic and circum-galactic
scales. I will report on the first systematic study of the molecular gas
properties in the host-galaxies of the most luminous quasars, fundamental
to probe the impact of SMBH feedback on the host-galaxy evolution. I will
show that luminous quasars pinpoint high-density sites where giant galaxies
assemble, and I will discuss the major contribution of mergers to the final
galaxy mass. To this aim, I will present a wealth of multi-wavelength (UV
to sub-millimeter) observations from the WISE/SDSS hyper-luminous quasars
survey  at z~2-5 (WISSH), and recent results from the ESO large program
XQR-30, the Ultimate X-SHOOTER Legacy Survey of Quasars at the Reionization
epoch.

 


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Tuesday April 27, 2021
Dr. Lorenzo Posti
Observatorie Astronomique de Strasbourg

Abstract

 

It is widely understood that galaxies use, throughout the Hubble time, only a small fraction of the baryons associated to their dark matter halos to form stars. Such low baryon-to-stars conversion efficiencies are expected in galaxy formation scenarios where stellar & AGN feedback play a key role in regulating star formation in galaxies, respectively at the low- and high-mass end.
In this talk I will show how we can constrain this scenario using galaxy dynamics. Both robust determinations of disc dynamical scaling relations (e.g. Tully-Fisher, mass-size) and accurate measurements of dark matter halo masses from HI rotation curves of spirals and from the kinematics of globular clusters around ellipticals, provide compelling evidence that the population of massive spirals has systematically larger baryon-to-stars conversion efficiencies than ellipticals. In fact, we see that the baryon-to-stars conversion efficiency monotonically increases with mass for late-type galaxies, while it shows a clear turn over at about L* only for early-type galaxies. Thus, while massive early types are compatible with standard stellar-to-halo mass relations based on abundance matching, massive late types are systematically discrepant from it.
I will discuss the possible repercussions that these results have, highlighting in particular what they imply in terms of AGN feedback and merging in galaxies of different types. Finally I will show that current state-of-the-art cosmological hydrodynamical simulations (EAGLE, TNG) still struggle to reproduce what we observe for the most massive discs.

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Thursday May 23, 2019
Patricia Sánchez Blázquez
Universidad Autónoma de Madrid

Abstract

The Time Inference with MUSE in Extragalactic Rings, TIMER, is a project dedicated to study the central regions
of 24 nearby galaxies with the integral field spectrograph MUSE. The spatial resolution of this instruments
allows the detailed study of the different structural components in these galaxies and, therefore, disentangle
their star formation histories, kinematics and dynamics of both, the gaseous and the stellar constituents.
In this talk, I will give an overview of the project as well as some details on  how the  dataset can be used for a plethora of scientific applications, like
understanding the stellar and AGN feedback, the role of primary and secondary bars, the dynamics of nuclear
spiral arms, barlenses, box/peanuts and bulges.


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Thursday January 15, 2015
Dr. Rosa Calvi
IAC

Abstract

One of the important questions in extragalactic astronomy concerns the debate between nature and nurture scenarios. Are the observed galaxy local properties the end product of the different conditions at birth or the product of the interactions, or other local processes, since a galaxy is not an isolated object? In this talk I will present the results of the analysis of some galaxy properties, morphologies and mass functions, obtained comparing, for the first time in a consistent manner, galaxies in the widest range of environments at low redshift (groups, clusters, binary systems, isolated galaxies). The aim was to understand the most important factors that drive galaxy evolution, trying to disentangle the importance of galaxy mass and global environment.

In addition I will present the first results concerning the two projects in which I am involved at IAC: the ALBA project, aimed to explore the signs of a proto-cluster at z~6.5, and the analysis of dust emission of a sample of local tadpole galaxies. 


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Wednesday November 12, 2014
Prof. Bruce G. Elmegreen
IBM Research Division

Abstract

The exponential radial profiles of spiral galaxies have been observed for decades with various explanations offered, but none of these explanations hold up now that the profiles have been traced to 10 scale lengths in some cases. Profiles with breaks also have their outer parts remarkably close to exponential. This is true in both spirals and dwarfs, with a particular problem for non-barred dwarfs where there are no strong torques or shears in the stellar disks for radial scattering. We have shown that scattering from disk clumps can make exponentials, and indeed dwarfs have fairly massive clumps and irregularities in their HI distributions. Spiral waves also have clumps in the form of persistent wave enhancements at corotation and at points of wave interference. This talk reviews the observations of exponential profiles and profile breaks in spiral and dwarf galaxies, and considers various theories to explain them.


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Wednesday November 5, 2014
Prof. Debra Meloy Elmegreen
Vassar College, Poughkeepsie, NY

Abstract

Galaxies at redshifts z~2-5 are dominated by clumpy morphologies instead of the more familiar elliptical and spiral types seen in the local Universe. The clumpy galaxies are gas-rich and highly turbulent, with star-forming regions 100 times more massive than in today’s galaxies. Clumpy galaxies should evolve into spirals and barred spirals when the disks become less turbulent. We find transitional types midway between clumpy and spiral, primarily around z~1-2. We observed local analogs of these transitional spirals in the Kiso Survey of Ultraviolet Galaxies, whose clumps are comparable in mass and surface density to the clumps at high redshift. We also find local analogs of high redshift tadpole galaxies, whose measured low metallicities in star-forming regions suggest ongoing external gas accretion.


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Thursday October 16, 2014
Dr. Lee Kelvin
University of Innsbruck

Abstract

What can the shape and size of a galaxy tell us about how it has evolved across cosmic time? Which evolutionary mechanisms are important, or relevant, and which not? How do galaxies form in the early Universe? As we enter a new era of big-data astronomy, our capacity to further pursue answers to these questions is increasingly limited not by Human ingenuity but by our use of 20th century data analysis techniques. In this talk, I will summarise my work with the Galaxy And Mass Assembly (GAMA) Survey in measuring the multi-wavelength light profile and stellar mass properties of ~200,000 galaxies in the local Universe. I will show how the stellar mass function may be broken down by morphology and structural component, and the implications this has for our understanding on which evolutionary mechanisms are important in shaping the galaxies around us over the course of the last 1 billion years. 


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Tuesday March 20, 2012
Miss Patricia S. Bessiere
University of Sheffield, UK

Abstract

The mechanism by which AGN activity is triggered has long been debated. One, often suggested, method of doing so is major, gas-rich mergers and galaxy interactions. I will present deep Gemini GMOS-S images of a sample of type II quasar host galaxies, demonstrating that 75% show clear signs that they are undergoing some kind of interaction. We compare these results with a control sample of quiescent early-type galaxies and find a similar rate of interaction (68%). However, we also find that the surface brightness of the features of the type II quasars are up to 2 mags brighter than those for the control sample, suggesting a difference in the types of mergers that the two groups are undergoing. We also compare our results with those for a sample of powerful radio galaxies and find very similar values for the surface brightness of the detected features.


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