"The formation histories and structures of massive galaxies at z > 2"
Ivo Labbe (Carnegie Observatories) - Nov 27 at 12:00 noon
One of the premier unsolved questions in cosmology is how massive
galaxies assembled their stars and central black holes. Multiwavelength
observations are now enabling us to address these questions directly
by studying massive galaxies during their main formation epoch
z = 1.5 - 3. Deep infrared imaging from Spitzer is playing a fundamental
role in these studies. I will discuss the constraints placed by IRAC,
MIPS, and X-ray observations on the stellar populations and AGN activity
in this crucial redshift range. A particular striking result is the photometric
identification of massive old galaxies at z>2 with very low specific
star formation rates, which appear to make up 30-40% of z~2.5
galaxies at the high mass end. Our follow-up studies with NICMOS show
that these old massive galaxies have remarkable structural properties,
presenting us with new puzzles about their structural evolution to low redshift.
Pushing to even higher redshifts, the unprecedented sensitivity of
Spitzer/IRAC has allowed us to probe the stellar-masses and ages of
galaxies at z > 7 in the Ultra Deep Field, providing a glimpse of the earliest
phases of galaxy formation. I will place these results in the context of
formation scenarios for massive galaxies, and look ahead to the future
with the expected launch of the far-IR Herschel Telescope, and the
installation of WFC3 on Hubble in the next 18 months.
The seminar will be held in 544 Campbell Hall.
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