The Norris Survey of the Corona Borealis Supercluster .2. Galaxy evolution with redshift and environment

We measure the field galaxy luminosity function (LF) as a function of color and redshift from z = 0 to z = 0.5 using galaxies from the Norris Survey of the Corona Borealis Supercluster. The data set consists of 603 field galaxies with 0 < z less than or equal to 0.5 and spans a wide range in apparent magnitude (14.0 less than or similar to r less than or similar to 21.5), although our field galaxy LF analysis is limited to 493 galaxies with r less than or equal to 20.0 mag. We use the observed g-r colors of the galaxies to compute accurate corrections to the rest B-AB and r bands. We find that our local r-band LF, when normalized to counts in high galactic latitude fields, agrees well with the local LF measured in the Las Campanas Redshift Survey. Our B-AB-band local LF, however, does not match the b(j)-band LF from the Stromlo/APM survey, having a normalization 1.6 times higher. We see compelling evidence that the B-AB-band held galaxy LF evolves with redshift. The evolution is strongest for the population of star-forming galaxies with [O II] lambda 3727 rest-frame equivalent widths greater than 10 Angstrom. The population of red, quiescent galaxies shows no sign of evolution to z = 0.5. The evolution of the LF that we observe is consistent with the findings of other faint galaxy redshift surveys. The fraction of galaxies with [O II] emission increases rapidly with redshift, but the fraction of galaxies with strong H delta absorption, a signature of a burst of star formation, does not. We thus conclude that the star formation in distant galaxies is primarily long-lived. We also compute the LFs of the Corona Borealis supercluster (z approximate to 0.07, 419 galaxies with 14.1 less than or equal to r less than or equal to 20.0 mag) and the Abell 2069 supercluster (z approximate to 0.11, 318 galaxies with 15.1 less than or equal to r less than or equal to, 20.0 mag). The shapes of the two supercluster luminosity functions are broadly similar to the shape of the local luminosity function. However, there are important differences. Both supercluster LFs have an excess of very bright galaxies. In addition, the characteristic magnitude of the Corona Borealis supercluster LF is roughly half a magnitude brighter than that of the local field galaxy LF, and there is a suggestion of an upturn in the LF for galaxies fainter than M(B-AB) similar to -17 + 5 log(10) h mag, where h is the Hubble constant in units of 100 km s(-1) Mpc(-1).