The Butcher-oemler Effect in 295 Clusters: Strong Redshift Evolution and Cluster Richness Dependence


We examine the Butcher-Oemler effect and its cluster richness dependence in the largest sample studied to date: 295 Abell clusters. We find a strong correlation between cluster richness and the fraction of blue galaxies, fB, at every redshift. The slope of the fB(z) relation is similar for all richnesses, but at a given redshift, fB is systematically higher… (More)


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