The Massive and Distant Clusters of WISE Survey XI: Stellar Mass Fractions and Luminosity Functions of MaDCoWS Clusters at $z \sim 1$

Abstract

We present stellar mass fractions and composite luminosity functions (LFs) for a sample of 12 clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS) at a redshift range of 0.951 ≤ z ≤ 1.43. Using SED fitting of optical and deep mid-infrared photometry, we establish the membership of objects along the lines-of-sight to these clusters and calculate the stellar masses of member galaxies. We find stellar mass fractions for these clusters largely consistent with previous works, including appearing to display a negative correlation with total cluster mass. We measure a composite 3.6 µm LF down to m * + 2.5 for all 12 clusters. Fitting a Schechter function to the LF, we find a characteristic 3.6 µm magnitude of m * = 19.83 ± 0.12 and faint-end slope of α = −0.81 ± 0.10 for the full sample at a mean redshift of z = 1.18. We also divide the clusters into high-and low-redshift bins at z = 1.29 and z = 1.06 respectively and measure a composite LF for each bin. We see a small, but statistically significant evolution in m * and α-consistent with passive evolution-when we study the joint fit to the two parameters, which is probing the evolution of faint cluster galaxies at z ∼ 1. This highlights the importance of deep IR data in studying the evolution of cluster galaxy populations at high-redshift.