Faint Galaxy Redshift Survey XVI : The Luminosity Function for Galaxies in the Region of the HDF - North to z = 1

We have carried out a study of the luminosity function (henceforth LF) of galaxies in the region of the HDF-North using our very complete redshift catalog. We divide the sample into five redshift bins covering the range 0.01 < z < 1.5 and consider three primary galaxy spectral classes. We solve for the LF at four rest frame wavelengths from 0.24 to 2.2μ. We find that the LFs for quiescent galaxies have shallow faint end slopes, while those of galaxies with detectable emission lines have steeper faint end slopes. Furthermore these slopes are independent of redshift out to z = 1.05 for each galaxy spectral grouping and agree well with comparable local determinations. We then fix α to obtain values of L for each galaxy spectral grouping as a function of redshift. We find that galaxies with strong absorption lines galaxies become brighter with z with Q ∼ 0.6 at all rest frame bands studied here, where Q = ∆log[L(z)]/∆z, while galaxies with detectable emission lines (i.e. star forming galaxies) show a smaller change in L with redshift at all bands, Q ∼ 0.3, with Q becoming significantly larger at rest frame 2400Å. Passive evolution models of galaxies are in reasonable agreement with these results for absorption line dominated galaxies, while plausible star formation histories can reproduce the behavior of the emission line galaxies. The major discrepancy with the specific set of galaxy spectral synthesis models we adopt, those of Poggianti (1997), is the prediction of much more luminosity fading at rest frame U for galaxies with a brief single initial burst of star formation than is actually inferred from our analysis of quiescent galaxies. We find the co-moving number density and stellar mass in galaxies to be approximately constant out to z ∼ 1.05, and with more uncertainty, to z ∼ 1.3. The major epoch(s) of star formation and of galaxy formation must have occurred even earlier. We confirm, with some uncertainty, that the UV luminosity density, an indicator of the star formation rate, increased by a factor of ∼5 over the period z = 0 to z = 1. Based in large part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California and NASA, Palomar Observatory, Mail Stop 105-24, California Institute of Technology, Pasadena, CA 91125