Galaxy populations in the most distant SPT-SZ clusters

II. Galaxy structural properties in massive clusters at 1.4 ≲ z ≲ 1.7

¹ INAF – Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34131 Trieste, Italy
e-mail: veronica.strazzullo@inaf.it
² Astronomy Unit, Department of Physics, University of Trieste, Via Tiepolo 11, 34131 Trieste, Italy
³ IFPU – Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
⁴ Faculty of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munich, Germany
⁵ Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
⁶ Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
⁷ INFN – National Institute for Nuclear Physics, Via Valerio 2, 34127 Trieste, Italy
⁸ Center for Astrophysics, Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138, USA
⁹ Department of Physics, University of Cincinnati, Cincinnati, OH 45221, USA
¹⁰ Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, Portsmouth PO1 3FX, UK
¹¹ Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110, USA
¹² Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
¹³ Department of Physics and Astronomy and PITT PACC, University of Pittsburgh, Pittsburgh, PA 15260, USA
¹⁴ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
¹⁵ School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
¹⁶ Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109, USA
¹⁷ Kavli Institute for Particle Astrophysics & Cosmology, Stanford University, PO Box 2450 Stanford, CA 94305, USA

Received: 22 October 2022
Accepted: 5 December 2022

Abstract

We investigate structural properties of massive galaxy populations in the central regions (< 0.7 r₅₀₀) of five very massive (M₂₀₀ > 4 × 10¹⁴ M_⊙), high-redshift (1.4 ≲ z ≲ 1.7) galaxy clusters from the 2500 deg² South Pole Telescope Sunyaev Zel’dovich effect (SPT-SZ) survey. We probe the connection between galaxy structure and broad stellar population properties at stellar masses of log(M/M_⊙) > 10.85. We find that quiescent and star-forming cluster galaxy populations are largely dominated by bulge- and disk-dominated sources, respectively, with relative contributions being fully consistent with those of field counterparts. At the same time, the enhanced quiescent galaxy fraction observed in these clusters with respect to the coeval field is reflected in a significant morphology-density relation, with bulge-dominated galaxies already clearly dominating the massive galaxy population in these clusters at z ∼ 1.5. At face value, these observations show no significant environmental signatures in the correlation between broad structural and stellar population properties. In particular, the Sersic index and axis ratio distribution of massive, quiescent sources are consistent with field counterparts, in spite of the enhanced quiescent galaxy fraction in clusters. This consistency suggests a tight connection between quenching and structural evolution towards a bulge-dominated morphology, at least in the probed cluster regions and galaxy stellar mass range, irrespective of environment-related processes affecting star formation in cluster galaxies. We also probe the stellar mass–size relation of cluster galaxies, and find that star-forming and quiescent sources populate the mass–size plane in a manner largely similar to their field counterparts, with no evidence of a significant size difference for any probed sub-population. In particular, both quiescent and bulge-dominated cluster galaxies have average sizes at fixed stellar mass consistent with their counterparts in the field.