Venice – Gregory RudnickMarch 2006 The Mean SED and Stellar Mass Density at z<3 Gregory Rudnick (NOAO, Tucson) Science Questions What is the evolution in the stellar populations of galaxies as an ensemble? How did stellar mass in galaxies accumulate over time? At each redshift, what kind of galaxies dominated the stellar mass density?

Venice – Gregory RudnickMarch 2006 NIR selected Distant Red Galaxies (DRGs) Selected to have J-K > 2.3  z > 2 Absent from UV selected samples Dominate massive galaxy population Franx et al. (2003); Förster Schreiber et al. (2004); Labbè et al. (2005); van Dokkum et al. (2006); Papovich et al. (2005); Reddy et al. (2005) Selected from Faint InfraRed Extragalactic Survey (FIRES) GR Ivo Labbè, OCIW, Pasadena Natascha Förster Schreiber, MPE, Garching Marijn Franx, Leiden Pieter van Dokkum, Yale Hans-Walter Rix, Heidelberg

Venice – Gregory RudnickMarch 2006 How to address Science Questions A comprehensive census of all stars Control field-to-field variance Emphasize consistent comparison to theory Ivo Labbè, Natascha Förster Schreiber, Stijn Wuyts, and the FIRES team

Venice – Gregory RudnickMarch fields with deep Optical/NIR data HDF-S MS GOODS-S HDF-N Calculate luminosity density in complete region L V limit Redshift bins Rudnick et al. submitted to ApJ

Venice – Gregory RudnickMarch 2006 Volume Averaged rest-frame SED of Luminous Galaxies non-DRGs DRGs Split by J-K color DRGs are redder at all wavelengths Color of the Universe is consistent with morphologically normal nearby galaxies

Venice – Gregory RudnickMarch 2006 The benefits of averaging

Venice – Gregory RudnickMarch 2006 Modeling the Mean SED Mean SED is well fit by simple models at all redshifts Strength of Breaks increasing with decreasing redshift redshift SSP  =300Myr CSF

Venice – Gregory RudnickMarch 2006 Evolution in  M/L V   M/L V  declines by a factor of 16 DRGs have higher M/L than non-DRGs

Venice – Gregory RudnickMarch 2006 density increase by factor of ~10 from z=3 to 0 under the integral of SFR(z) (from UV) DRGs contribute significantly to stellar mass budget at 1.6<z<3 Still large field-to-field variations Observed  * Evolution

Venice – Gregory RudnickMarch 2006 Comparison with Models Disagreement in relative evolution Are observations missing mass? Perform consistent comparison with models Model predictions are in poor agreement even when observational selection is applied Springel & Hernquist 2003 Finlator et al Croton et al. 2005

Venice – Gregory RudnickMarch 2006 Conclusions Volume averaged SED evolves monotonically to redder colors from z = 3 to 0. Mean SED at all redshifts is consistent with morphologically normal local galaxies. Total mass density increases by ~10 from z = 3 to 0 UV-selected samples miss more than 50% of mass in luminous galaxies Consistently compared models fail to match observations.