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OATS-DAUT SEMINAR
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Speaker:
Gary Mamon (Institut d'Astrophysique de Paris, F)
Title:
How do galaxies get their mass and when do they form their stars?
Date: Wednesday, October 27th, 2010
Time: 15:00
Venue: Villa Bazzoni
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Abstract:
Simple toy models of galaxy formation are
presented where the stellar mass of a galaxy only depends on its halo
mass and redshift. These models show that there exists a fairly narrow
range of halo masses in which galaxies can efficiently accrete gas and
retain it against the feedback from supernovae and AGN jets. We apply
such a model to the halos and subhalos extracted from a high
resolution cosmological simulation, merging the galaxies after a delay
set by dynamical friction. We show that by fitting the z=0 galaxy
stellar mass function, we are also able to reproduce fairly well the
two-component (central+satellites) galaxy stellar mass functions
observed in the SDSS in narrow bins of halo mass, as well as the
strong dependence of galaxy properties on their stellar mass, and the
evolution of the cosmic star formation rate. The relative importance
of gas accretion vs. mergers decreases with their z=0 stellar mass,
and the highest mass galaxies are built by dry major mergers. We apply
the same toy model to the halos of a halo-merger tree to show that the
frequency of blue compact dwarf galaxies in the local Universe with
mostly very young stellar populations appears to match the
observations, and discuss the ages of dwarf spheroidals.
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contact: Andrea Biviano (OATS)