The Evolution of Dusty Star Formation and Stellar Mass Assembly in Clusters: Results from the IRAC 3.6, 4.5, 5.8, and 8.0 μm Cluster Luminosity Functions

Abstract

We present a catalog of 99 candidate clusters and groups of galaxies in the redshift range 0.1 < z_(phot) < 1.3 discovered in the Spitzer FLS. The clusters are selected by their R_c − 3.6 μm galaxy color-magnitude relation using the cluster red-sequence algorithm. Using this cluster sample, we compute the 3.6, 4.5, 5.8, and 8.0 μm cluster LFs. Similar to previous studies, we find that for the bands that trace stellar mass at these redshifts (3.6 and 4.5 μm) the evolution in M* is consistent with a passively evolving population of galaxies with a high formation redshift (z_f > 1.5). Using the 3.6 μm LF as a proxy for stellar luminosity, we remove this component from the MIR (5.8 and 8.0 μm ) cluster LFs and measure the LF of dusty star formation/AGNs in clusters. We find that at z < 0.4 the bright end of the cluster 8.0 μm LF is well described by a composite population of quiescent galaxies and regular star-forming galaxies with a mix consistent with typical cluster blue fractions; however, at z > 0.4, an additional population of dusty starburst galaxies is required to properly model the 8.0 μm LFs. Comparison to field studies at similar redshifts shows a strong differential evolution in the field and cluster 8.0 μm LFs with redshift. At z ~ 0.65 8.0 μm -detected galaxies are more abundant in clusters compared to the field, but thereafter the number of 8.0 μm sources in clusters declines with decreasing redshift, and by z ~ 0.15, clusters are underdense relative to the field by a factor of ~5. The rapid differential evolution between the cluster and field LFs is qualitatively consistent with recent field galaxy studies that show that the star formation rates of galaxies in high-density environments are larger than those in low-density environments at higher redshift.