The DEEP evolutionary exploratory probe 2 galaxy redshift survey: The galaxy luminosity function to z sim; 1¹

The evolution of the 5-band galaxy luminosity function is measured using a sample of more than 11,000 galaxies with spectroscopic redshifts from the DEEP2 Redshift Survey. The rest-frame MB versus U - B color-magnitude diagram of DEEP2 galaxies shows that the color-magnitude bimodality seen in galaxies locally is still present at redshifts z > 1. Dividing the sample at the trough of this color bimodality into predominantly red and blue galaxies, we find that the luminosity function of each galaxy color type evolves differently. Blue counts tend to shift to brighter magnitudes at constant number density, while the red counts remain largely constant at a fixed absolute magnitude. Using Schechter functions with fixed faint-end slopes we find that M_B* for blue galaxies brightens by ∼ 1.3 ± 0.14 mag per unit redshift, with no significant evolution in number density. For red galaxies M_B* brightens somewhat less with redshift, while the formal value of Φ* declines. When the population of blue galaxies is subdivided into two halves using the rest-frame color as the criterion, the measured evolution of both blue subpopulations is very similar.