We analyse the evolution of environmental quenching efficiency, the fraction of quenched cluster galaxies that would be star-forming if they were in the field, as a function of redshift in 14 spectroscopically confirmed galaxy clusters with 0.87 < z < 1.63 from the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS). The clusters are the richest in the survey at each redshift. Passive fractions rise from 42−13+10\% at z ~ 1.6 to 80−9+12\% at z ~ 1.3 and 88−3+4\% at z < 1.1, outpacing the change in passive fraction in the field. Environmental quenching efficiency rises dramatically from 16−19+15 at z ~ 1.6 to 62−15+21%atz1.3and73_{-7}^{+8}%atz\lesssim$ 1.1. This work is the first to show direct observational evidence for a rapid increase in the strength of environmental quenching in galaxy clusters at z ~ 1.5, where simulations show cluster-mass halos undergo non-linear collapse and virialisation.
@article{arxiv.1610.08058,
title = {Evidence for strong evolution in galaxy environmental quenching efficiency between z = 1.6 and z = 0.9},
author = {Julie B. Nantais and Adam Muzzin and Remco F. J. van der Burg and Gillian Wilson and Chris Lidman and Ryan Foltz and Andrew DeGroot and Allison Noble and Michael C. Cooper and Ricardo Demarco},
journal= {arXiv preprint arXiv:1610.08058},
year = {2016}
}