Stellar mass function of cluster galaxies at z ~ 1.5: Evidence for reduced quenching efficiency at high redshift

We present the stellar mass functions (SMFs) of passive and star-forming galaxies with a limiting mass of 10^10.1M_Ȯ in four spectroscopically confirmed Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) galaxy clusters at 1.37 <z< 1.63. The clusters have 113 spectroscopically confirmed members combined, with 8-45 confirmed members each. We construct Ks-band-selected photometric catalogs for each cluster with an average of 11 photometric bands ranging from u to 8 μm. We compare our cluster galaxies to a field sample derived from a similar Ks-band-selected catalog in the UltraVISTA/COSMOS field. The SMFs resemble those of the field, but with signs of environmental quenching. We find that 30 ± 20% of galaxies that would normally be forming stars in the field are quenched in the clusters. The environmental quenching efficiency shows little dependence on projected cluster-centric distance out to ~4 Mpc, providing tentative evidence of pre-processing and/or galactic conformity in this redshift range. We also compile the available data on environmental quenching efficiencies from the literature, and find that the quenching efficiency in clusters and in groups appears to decline with increasing redshift in a manner consistent with previous results and expectations based on halo mass growth.