29 March 2007
29 March 2007
Speaker: David Sanders (University of Hawaii)
The Origin and Evolution of Luminous Infrared Galaxies: new results from
the Spitzer-COSMOS survey.
New multi-wavelength studies of complete samples of luminous infrared galaxies (LIGs)
in the local universe confirm that strong interactions/mergers of gas-rich spirals provide the
trigger for the intense infrared luminosity, and that the most luminous objects are intimately
related to intense nuclear starbursts and the the rapid growth of super massive black holes.
The Spitzer-COSMOS survey of the HST-ACS 2sqdeg field is designed to extend the detailed
multi-wavelength studies of LIGs out to higher redshifts, and more generally, to provide an
infrared view of galaxies for comparison with that seen in the optical. Early science results
from S-COSMOS suggest that the deep optical surveys have indeed missed an important
class of extragalactic objects ! S-COSMOS MIPS-24 results clearly reveal a substantial
population of infrared luminous galaxies which fill the optical "green valley" . These infrared
selected objects appear to provide a plausible evolutionary connection between galaxies in
the "blue cloud" (starburst disks) and "red sequence" (old stars/ellipticals) -- the
bimodal distribution which characterizes the extragalactic population seen in the optical.
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