At the Vigintennial of the Butcher-Oemler Effect

Abstract

In their study of the evolution of galaxies within clusters, Butcher and Oemler discovered evidence for a strong evolution in star-formation rate with redshift. Later studies confirmed this conclusion and uncovered several aspects of the effect: photometric, spectroscopic, and morphological. This article reviews a broad sample of these works and discusses selection effects, biases, and driving mechanisms that might be responsible for the changes in star-formation rate.

15 pages. 4 figures. Refereed review based upon colloquia delivered at UQ. Accepted for publication in PASA; Minor alterations made to conform more closely to published version