Monday, January 9, 2012
4:00 pm
Cahill, Hameetman Auditorium – Cahill Center for Astronomy and Astrophysics
Astronomy Tea Talk
Series:Astronomy Tea Talks
The Physical Origin of Cool Gas in Massive Halos
Jean-Rene Gauthier, Caltech
Characterizing the structure and evolution of the cool gas in dark matter halos
is a key element in current models of galaxy formation. Several physical mechanisms
have been introduced to explain the origin of the cool, T ∼ 1e4 K gas in the dark
matter halos of normal galaxies. Some of these mechanisms include cold accretion
from the IGM, gas-rich galaxy mergers, starburst driven outflows, and thermal
instabilities generated within the hot coronal gas. Unfortunately, direct empirical
data are lacking and these mechanisms remain poorly constrained. My talk focuses on
the empirical determination of the cool gas content of massive dark matter and
directly addresses the physical origin of the gas. Specifically, I will present
a series of empirical constraints on the cool gas content of dark matter halos
hosting Luminous Red Galaxies (LRGs) at z ≈ 0.5. In my talk, I will describe
the outcome of a clustering analysis done on a population of MgII absorption
doublets and its implications for the presence of cool gas in massive halos.
I will then describe the main results of an on-going spectroscopic survey of
LRGs and present measurements of the covering fraction of cool gas in these
galaxies. I will also present the results of a stellar population synthesis
analysis done on a sample of spectroscopic LRGs. This analysis allows me to
directly assess whether or not there is a connection between the presence
of the gas and the recent star formation activities of the galaxies. Finally,
I will briefly introduce on-going projects to fully explore the physical
origin of the gas in more details.
Contact Gina Armas gina@its.caltech.edu at 4671
For more information see http://www.astro.caltech.edu/~gma/colloquia.html
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