The Canada-France Redshift Survey. VI. Evolution of the Galaxy Luminosity Function to Z approximately 1

The cosmic evolution of the field galaxy population has been studied out to a redshift of z ∼ 1 using a sample of 730 I-band selected galaxies, of which 591 have secure redshifts with median ∼ 0.56. The trivariate luminosity function φ(M, color, z) shows unambiguously that the population evolves and that this evolution is strongly differential with color and, less strongly, with luminosity. The luminosity function of red galaxies shows very little change in either number density or luminosity over the entire redshift range 0 <z < 1. In contrast, the luminosity function of blue galaxies shows substantial evolution at redshifts z > 0.5. By 0.5 <z <0.75 the blue luminosity function appears to have uniformly brightened by approximately 1 mag. At higher redshifts, the evolution appears to saturate at the brightest magnitudes but continues at fainter levels, which leads to a steepening of the luminosity function. A significant excess of galaxies relative to the local luminosity function described by Loveday et al. in 1992 is seen at low redshifts z <0.2 around M_AB(B) ∼ -18, and these galaxies may possibly represent the descendants of the evolving blue population seen at higher redshifts. The changes seen in the luminosity function are also apparent in color-magnitude diagrams constructed at different epochs and in the V/V_max statistic computed as a function of spectral type. Finally, it is argued that the picture of galaxy evolution presented here is consistent with the very much smaller samples of field galaxies that have been selected in other wave bands and with the results of studies of galaxies selected on the basis of Mg II λ2799 absorption.