THE RED-SEQUENCE LUMINOSITY FUNCTION IN MASSIVE INTERMEDIATE-REDSHIFT GALAXY CLUSTERS

We measure the rest-frame B-band luminosity function of red-sequence galaxies of five intermediate-redshift (0.5 < z < 0.9), high-mass (sigma > 950 km s(-1)) clusters. Cluster galaxies are identified through photometric redshifts based on imaging in seven bands (five broad and two narrow) using the WIYN 3.5 m telescope. The luminosity functions (LFs) are well-fit down to M-B(*)+3 for all of the clusters out to a radius of R-200. For comparison, the LFs for a sample of 59 low-redshift clusters selected from the Sloan Digital Sky Survey are measured as well. There is a brightening trend (M-B(*) increases by 0.7 mag at z = 0.75) with redshift comparable to what is seen in the field for similarly defined galaxies, although there is a hint that the cluster red-sequence brightening is more rapid in the past (z > 0.5), and relatively shallow at more recent times. Contrary to other claims, we find little evidence for evolution of the faint-end slope. Previous indications of evolution may be due to limitations in measurement technique, bias in the sample selection, and cluster-to-cluster variation. As seen in both the low- Wand highredshift samples, a significant amount of variation in LF parameters alpha and M-* exists between individual clusters.