Dr. Pablo G. Perez-Gonzalez, University of Arizona - Steward Observatory

University of Florida Astronomy Colloquium - Sep 2nd, 2005

Spitzer view on the evolution of star-forming galaxies from z=0 to z=3

I will present the cosmological surveys we are carrying out at the University of Arizona using the IRAC and MIPS instruments on Spitzer. The mid- and far-IR Spitzer data in the Chandra Deep Field South and the Hubble Deep Field North are combined with publicly available UV, optical, and near-IR observations to study the evolution of star-forming galaxies from z=0 to z=3. We obtain photometric redshifts, SFRs (using IR luminosities), and stellar masses (using rest-frame K-band observations) for more than 8,000 galaxies. For the first time ever, we are able to build a Lilly-Madau plot (time evolution of the SFR density of the Universe) with 9 points from z=0 to z=3 using a homegeneously selected sample and a SFR estimator not affected by dust attenuation. We also study the mass assembly of galaxies in the same redshift range, obtaining results that support a 'downsizing' scenario in galaxy formation