Evolution of Galactic Disks in Clusters and the Field at 0.1 < [ITAL]z[/ITAL] < 0.6 in the CNOC Survey

Abstract

Two-dimensional surface photometry is presented for a sample of 351 late-type galaxies with 0.12 < z < 0.65. These objects are drawn from the Canadian Network for Observational Cosmology (CNOC) cluster survey and are either spectroscopically confirmed members of clusters at z = 0.23 (64 galaxies), 0.43 (45), and 0.55 (36) or field galaxies with similar redshifts. Galaxies in the rich cluster Abell 2256 at z = 0.06 were also analyzed with the same methods to provide a local reference point. At redshifts of (0.23, 0.43, 0.55) the disk surface brightness in cluster late-type galaxies is higher in the B band by Δμ0(B) = (-0.58 ± 0.12, -1.22 ± 0.17, -0.97 ± 0.2) mag, respectively, relative to the Freeman (1970) constant surface brightness relation; whereas disks in cluster galaxies at z = 0.06 are consistent with that relation. Field galaxies show a progressive disk brightening with redshift that is consistent with that seen in the cluster population. Taken together with similar measurements of early-type galaxies, these results suggest that the evolution of the field and cluster galaxy populations are similar, although we emphasize that our sample of cluster galaxies is dominated by objects at large distances (up to 3 Mpc) from the dense cluster core, so that the implications of these findings with respect to the Butcher-Oemler effect and the morphology-density relation will not be clear until an analysis of galaxy properties as a function of clustercentric distance is completed.