Evidence for strong evolution in galaxy environmental quenching efficiency between z = 1.6 and z = 0.9

TL;DR

This study provides observational evidence that the efficiency of environmental quenching in galaxy clusters significantly increases from redshift 1.6 to 1.1, indicating rapid evolution in galaxy evolution processes during this epoch.

Contribution

It is the first work to directly observe a rapid increase in environmental quenching efficiency in galaxy clusters around z ~ 1.5, linking it to cluster formation processes.

Findings

Passive galaxy fractions increase from ~42% at z~1.6 to ~88% at z<1.1.

Environmental quenching efficiency rises from ~16% at z~1.6 to ~73% at z<1.1.

Strong evolution in quenching efficiency correlates with cluster formation stages.

Abstract

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}\% at z ~ 1.3 and $73_{-7}^{+8}$\% at z $\lesssim$ 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.