The Red Sequence Luminosity Function in Massive Intermediate Redshift Galaxy Clusters

TL;DR

This study measures the luminosity function of red-sequence galaxies in massive galaxy clusters at intermediate redshifts, revealing a brightening trend with redshift and significant variation among clusters, challenging previous claims of evolution in the faint end slope.

Contribution

It provides new measurements of the red-sequence luminosity function at intermediate redshifts and compares them with low-redshift clusters, highlighting variations and challenging prior assumptions about faint-end evolution.

Findings

Brightening of M_B^* by 0.7 mags at z=0.75

Little evidence for evolution of faint end slope

Significant cluster-to-cluster variation in luminosity function parameters

Abstract

We measure the rest-frame B-band luminosity function of red-sequence galaxies (RSLF) of five intermediate-redshift (0.5 < z < 0.9), high-mass (sigma > 950 km/s) clusters. Cluster galaxies are identified through photometric redshifts based on imaging in seven bands (five broad, and two narrow) using the WIYN 3.5m telescope. The luminosity functions are well-fit down to M_B^*+3 for all of the clusters out to a radius of R_200. For comparison, the luminosity functions for a sample of 59 low redshift clusters selected from the SDSS are measured as well. There is a brightening trend (M_B^* increases by 0.7 mags by 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 and high redshift sample, a significant amount of variation in luminosity functions parameters alpha and M^* exists between individual clusters.