The GOGREEN Survey: Evidence of an Excess of Quiescent Disks in Clusters at 1.0 < z < 1.4

Abstract We present the results of the measured shapes of 832 galaxies in 11 galaxy clusters at 1.0 10.1 ≤ log ( M / M ⊙ ) 10.5 where clusters show a flatter distribution, with an excess at low q . Modelling the distribution with oblate and triaxial components, we find that the cluster and field sample difference is consistent with an excess of flattened oblate quiescent galaxies in clusters. The oblate population contribution drops at high masses, resulting in a narrower q distribution in the massive population than at lower masses. Using a simple accretion model, we show that the observed q distributions and quenched fractions are consistent with a scenario where no morphological transformation occurs for the environmentally quenched population in the two intermediate-mass bins. Our results suggest that environmental quenching mechanism(s) likely produce a population that has a different morphological mix than those resulting from the dominant quenching mechanism in the field.