Revisiting Brightest Cluster Galaxy Evolution with the Las Campanas Distant Cluster Survey

Abstract

We investigate the influence of environment on brightest cluster galaxy (BCG) evolution using a sample of 63 clusters at 0.3 < z < 0.9 drawn primarily from the Las Campanas Distant Cluster Survey and follow-up V, I, and K' photometry. The luminosity evolution of the entire BCG sample is not adequately described by a single evolutionary model. Using the integrated light from the cluster detection as a proxy for cluster Lx and the suggestion by Burke, Collins, & Mann, we set Lx = 2 x 10^{44} ergs/s to be the division between high and low luminosity clusters. At high redshift (z>0.6) BCGs from low-Lx clusters are fainter, on average, than those from high-Lx clusters and are best modeled as having constant luminosity with redshift. The BCGs from high-Lx cluster are best modeled as having a stellar population that formed at large redshift (z_form > 5) and is passively evolving. However, for the entire BCG population, the observed V-I and I-K' colors are well described by a single evolutionary model in which the stellar populations have z_form > 5 and subsequently passively evolve. We conclude that accretion is proportionally more significant for BCGs in lower mass clusters at these redshifts (factor of 2 to 4 increase in mass since z ~ 1 for the low Lx systems) and that the accreted matter is in the form of systems with evolved stellar populations.