Found 6 talks width keyword massive galaxies

Thursday June 25, 2020
Prof. Francesco Shankar
University of Southampton


It has been claimed for decades that almost all galaxies in the local Universe host at their centre a supermassive black hole (SMBH) the mass of which appears to be tightly correlated with the stellar mass and the random motion ("velocity dispersion", sigma) of the stars in the host galaxy. In this talk I will first review the state of the art in this field. I will then highlight that significant biases affect local black hole-galaxy correlations.  I will specifically show that the majority of quiescent early-type galaxies with central black hole dynamical mass estimates have significantly higher velocity dispersions than local typical galaxies of similar stellar mass. Through aimed Monte Carlo simulations, residual analysis, and the comparison with latest AGN clustering measurements, I will then illustrate that present data sets of active and quiescent galaxies strongly favour on average lower SMBH masses than previously thought, and point to velocity dispersion as more ``fundamental'' than galaxy stellar mass, galaxy size or Sérsic index. I will then move on discussing the main implications of these findings, in particular: 1) The implied black hole radiative efficiencies and obscured fractions; 2) the consequences on feedback from active black holes and SMBH binary gravitational waves; 3) the connection to cosmological models that rely on velocity dispersion, rather than stellar mass, as main driver of black hole growth.

Zoom link:

Thursday June 13, 2013
Dr. Itziar Aretxaga


AzTEC is a sensitive bolometer camera that, coupled with 10-15m-class sub-mm telescopes, has mapped more than 3 sq. deg of the extragalactic sky to depths between 0.7 and 1.1 mJy at 1.1mm, prior to its current installation and operation on the 32m Large Millimeter Telescope (LMT). These extragalactic surveys targeted towards blank-fields and biased high-z environments alike have allowed us to identify regions of the sky where submillimeter galaxies (SMGs), powerful obscured starbursts at high-redshifts (z>1), cluster, and possibly mark the potential wells of accelerated galaxy-formation that will eventually form massive clusters. In this talk I will describe the evidence we have found for these overdense regions of massive galaxies, their structure and possible interpretation, as well as the follow-up observations we are carrying out with the LMT nowadays.

Thursday July 5, 2012
Dr. Ignacio Ferreras
University College of London


Massive early-type galaxies constitute an ideal test bed to probe our understanding of galaxy formation and evolution. Their high mass, spheroidal morphology and overly old stellar populations, along with their presence over a wide range of redshifts put to the test our current paradigm of formation via hierarchical growth. In this talk I will review recent work focused on the dark and bright sides of this problem. The former is tackled via gravitational lensing, comparing the dark matter and luminous components out to several effective radii, probing the efficiency of baryon collapse and ejection, and its feedback on the dark matter distribution (adiabatic compression). The bright side of early-type galaxies is approached via photo-spectroscopic analyses of the stellar populations, revealing a complex formation and assembly history with two well-defined phases of growth, and an intriguing connection with the "microphysics" of star formation.

Monday December 20, 2010
Mr. Fernando Buitrago Alonso
University of Nottingham, UK


Massive (≥ 1011 M⊙) galaxies at high redshift (z ≥ 1.5) remain mysterious objects. Their extremely small sizes (effective radii of 1-2 kpc) make them as dense as modern globular clusters. It is thought that a highly dissipational merger is needed to create such compact type of galaxies. We will discuss this issue, along with state-of-the-art morphological and kinematic observations of these objects. In the present day Universe massive galaxies show large sizes, and harbor old and metal-rich stellar populations. In order to explore their development, we present near-IR IFU observations with SINFONI@VLT for ten massive galaxies at z=1.4 solely selected by their high stellar mass which allow us to retrieve velocity dispersions, kinematic maps and dynamical masses. We joined this with data and works coming from the GOODS NICMOS Survey, the largest sample of massive galaxies (80 objects) with high-resolution imaging at high redshift (1.7 < z < 3) acquired to date. As a result, we show how their morphology changes possibly through elusive minor merging.

Thursday July 16, 2009
Prof. David Koo
University of California Observatories, Lick Observatory, USA


AEGIS (All-wavelength Extended Groth strip International Survey: is on-going survey that opens up new views of the development of galaxies and AGN's at redshifts z about 1. AEGIS is panchromatic like GOODS, with coverage ranging from X-ray to radio, and nearly as deep but more panoramic by covering a 4x larger region. Its backbone is the most Northern (accessible to the GTC) of the four fields of the DEEP2 Keck spectroscopic survey, which provides not only precision redshifts that yield reliable pairs, groups, and environments, but also internal kinematics and chemical abundances. After an overview of the DEEP and AEGIS surveys, I will share some recent highlights, including using a new kinematic measure for distant galaxies to track Tully-Fisher-like evolution; discovering metal poor, massive, luminous galaxies; finding ubiquitous galactic gas outflows among distant star forming galaxies; and exploring the nature of distant x-ray AGNs.

Wednesday January 21, 2009
Dr. Nadine Neumayer
European Southern Observatory, Garching, Germany


The centers of massive galaxies are special in many ways, not least because all of them are believed to host supermassive black holes. Since the discovery of a number of relations linking the mass of this central black hole to the large scale properties of the dynamically hot component of its host galaxy (bulge) it has become clear that the growth of the central black hole is intimately connected to the evolution of its host galaxy. However, for bulge-less galaxies, the situation is much less clear. Interestingly, these galaxy often host star clusters in their nuclei, and unlike black holes, these nuclear star clusters provide a visible record of the accretion of stars and gas into the nucleus. I will present my ongoing projects on nuclear star clusters that aim to understand their formation process and might give a hint on how black holes get to the centers of galaxies.

« Newer Older »

Upcoming talks

No talks scheduled for the next days.

Recent Colloquia