Chan, JeffreyWilson, GillianBalogh, MichaelRudnick, Gregoryvan der Burg, Remco F. J.Muzzin, AdamWebb, KristiBiviano, AndreaCerulo, PierluigiCooper, M CLidman, Christopher2024-03-192024-03-190004-637Xhttp://hdl.handle.net/1885/316142We present the results of the measured shapes of 832 galaxies in 11 galaxy clusters at 1.0 < z < 1.4 from the GOGREEN survey. We measure the axis ratio (q), the ratio of the minor to the major axis, of the cluster galaxies from near-infrared Hubble Space Telescope imaging using Sersic profile fitting and compare them with a field sample. We find that the median q of both star-forming and quiescent galaxies in clusters increases with stellar mass, similar to the field. Comparing the axis ratio distributions between clusters and the field in four mass bins, the distributions for star-forming galaxies in clusters are consistent with those in the field. Conversely, the distributions for quiescent galaxies in the two environments are distinct, most remarkably in 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.This work is supported by HST program number GO-15294, and by grant No. 80NSSC17K0019 issued through the NASA Astrophysics Data Analysis Program (ADAP) as well as NSF grants AST-1815475, AST-1517863 and AST-1518257. Support for program number GO-15294 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. B.V. acknowledges funding from the INAF main-stream funding program (PI B. Vulcani) and from the Italian PRIN-Miur 2017 (PI A. Cimatti). J.N. acknowledges support from Universidad Andres Bello internal grant DI-12-19/R.application/pdfen-AU© 2021 The authorshttp://creativecommons.org/licenses/by/4.0/Galaxy evolutionGalaxy clustersHigh-redshift galaxy clusters202110.3847/1538-4357/ac11172022-11-13