Description
We study the evolution of the red-galaxy fraction (f_red_) in 905 galaxy groups with 0.15<=z<0.52. The galaxy groups are identified by the "probability friends-of-friends" algorithm from the first Red-Sequence Cluster Survey (RCS1) photometric-redshift sample. There is a high degree of uniformity in the properties of the red sequence of the group galaxies, indicating that the luminous red-sequence galaxies in the groups are already in place by z~0.5 and that they have a formation epoch of z>~2. In general, groups at lower redshifts exhibit larger f_red_ than those at higher redshifts, showing a group Butcher-Oemler effect. We investigate the evolution of f_red_ by examining its dependence on four parameters, one of which can be classified as intrinsic and three of which can be classified as environmental: galaxy stellar mass (M_*_), total group stellar mass (M_*,grp_, a proxy for group halo mass), normalized group-centric radius (r_grp_), and local galaxy density ({Sigma}_5_).
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