The Rest‐Frame Optical Luminosity Density, Color, and Stellar Mass Density of the Universe fromz= 0 toz= 3

We present the evolution of the rest-frame optical luminosity density, of theintegrated rest-frame optical color, and of the stellar mass density for asample of Ks-band selected galaxies in the HDF-S. We derived the luminositydensity in the rest-frame U, B, and V-bands and found that the luminositydensity increases by a factor of 1.9+-0.4, 2.9+-0.6, and 4.9+-1.0 in the V, B,and U rest-frame bands respectively between a redshift of 0.1 and 3.2. Wederived the luminosity weighted mean cosmic (U-B)_rest and (B-V)_rest colors asa function of redshift. The colors bluen almost monotonically with increasingredshift; at z=0.1, the (U-B)_rest and (B-V)_rest colors are 0.16 and 0.75respectively, while at z=2.8 they are -0.39 and 0.29 respectively. We derivedthe luminosity weighted mean M/LV using the correlation between (U-V)_rest andlog_{10} M/LV which exists for a range in smooth SFHs and moderate extinctions.We have shown that the mean of individual M/LV estimates can overpredict thetrue value by ~70% while our method overpredicts the true values by only ~35%.We find that the universe at z~3 had ~10 times lower stellar mass density thanit does today in galaxies with LV>1.4 \times 10^{10} h_{70}^-2 Lsol. 50% of thestellar mass of the universe was formed by $z~1-1.5. The rate of increase inthe stellar mass density with decreasing redshift is similar to but above thatfor independent estimates from the HDF-N, but is slightly less than thatpredicted by the integral of the SFR(z) curve.Comment: 19 pages, 12 figures, Accepted for Publication in the Dec. 20, 2003 edition of the Astrophysical Journal. Minor changes made to match the accepted version including short discussions on the effects of clustering and on possible systematic effects resulting from photometric redshift error