The Bright Ages Survey. II. Evolution of Luminosity, Dust Extinction, and Star Formation from z = 0.5 to z = 2.5^*

The Bright Ages Survey is a K-band-selected redshift survey over six separate fields with UBVRIzJHK imaging covering a total of 75.6 arcmin ² and reaching K = 20-20.5. Two fields have deep HST imaging, while all are centered on possible overdensities in the z ~ 2 range. Here we report photometric redshifts and spectroscopy for this sample, which has been described in Paper I. We find 18 galaxies with spectroscopic redshifts of z > 1.5. The derived rest-frame R-band luminosity functions show strong evolution out to z = 2. The luminosity function at z = 2 shows more bright galaxies than at any other epoch, even the extrapolated z = 3 luminosity function from Shapley et al. However, the R-band integrated luminosity density remains roughly constant from to z = 0.5 to z = 2. Evolved galaxies (E, S0, Sa) show a decreasing contribution to the total R-band luminosity density with redshift. The dust extinction in our K-selected sample is moderately larger [median z = 2 E(B - V) = 0.30] than that found in Lyman break galaxies, although not enough to make a significant impact on the total light or star formation found at high redshift. We measure the extinction-corrected star formation rate density at z = 2, finding ρ_SFR(z = 1.5-2.5) = 0.093 M_☉ yr^-1 Mpc^-3, consistent with a relatively flat instantaneous star formation rate from z = 1-4.