Stellar mass function of cluster galaxies at z $\sim$ 1.5: evidence for reduced quenching efficiency at high redshift

TL;DR

This study examines the stellar mass functions of galaxies in clusters at z~1.5, revealing that environmental quenching is less efficient at high redshift, with implications for galaxy evolution models.

Contribution

It provides the first detailed comparison of cluster and field galaxy SMFs at z~1.5, highlighting reduced quenching efficiency and environmental effects at this epoch.

Findings

Cluster SMFs resemble field but show signs of environmental quenching.

Approximately 30% of galaxies are quenched in clusters compared to the field.

Quenching efficiency decreases with increasing redshift, consistent with halo growth models.

Abstract

We present the stellar mass functions (SMFs) of passive and star-forming galaxies with a limiting mass of 10$^{10.1}$ M$_{\odot}$ 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 $\mu$m. 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 $\pm$ 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 $\sim$ 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.