MEASURING THE AVERAGE EVOLUTION OF LUMINOUS GALAXIES AT z < 3: THE REST-FRAME OPTICAL LUMINOSITY DENSITY, SPECTRAL ENERGY DISTRIBUTION, AND STELLAR MASS DENSITY

摘要

We present the evolution of the volume-averaged properties of the rest-frame optically luminous (L_V > 3 x 10~(10) h_(70)~(-2) solar luminosity) galaxy population to z ～ 3, determined from four disjoint deep fields. We characterize their rest-frame UV through optical properties via the mean SED. To measure evolution, we apply the selection criteria to a sample of galaxies from the SDSS and COMBO-17 survey. The mean rest-frame 2200 A through V-band SED becomes steadily bluer with increasing redshift, but at all redshifts z < 3 the mean SED falls within the range defined by "normal" galaxies in the nearby universe. We measure the mean stellar mass-to-light ratios (M_*/L) and stellar mass densities (ρ_*) by fitting models to the mean rest-frame UV-optical SEDs. The ρ_* in galaxies selected at a fixed luminosity has increased by a factor of 3.5-7.9 from z = 3 to 0.1. If we instead use our observed M_*/L_V evolution to select galaxies at a fixed mass, ρ_* evolves by a factor of 5.3-16.7. After correcting to total, the measured ρ_* at z < 2 lie below the integral of the star formation rate density as a function of redshift as derived from UV-selected samples after a standard correction for extinction. We find large discrepancies between recent model predictions for the evolution of ρ_* and our results, even when our observational selection is applied to the models. Finally, we determine that distant red galaxies (selected to have J_s - K_s > 2.3) in our L_V~(rest)-selected samples contribute 30% and 64% of the stellar mass budget at z ～ 2 and z ～ 2.8, respectively. These galaxies are largely absent from UV surveys, and this result highlights the need for mass selection of high-redshift galaxies.