SPT-CL J0205–5829: A z = 1.32 Evolved Massive Galaxy Cluster in the South Pole Telescope Sunyaev-Zel'dovich Effect Survey

• Published in: The Astrophysical Journal
• Main Authors: Stalder, B., Lueker, M., Padin, S., Shirokoff, E., Vieira, J. D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Astronomical Society 2013
• Subjects: South Pole; South pole
• Online Access: https://authors.library.caltech.edu/37083/; https://authors.library.caltech.edu/37083/1/0004-637X_763_2_93.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20130222-131740719

The galaxy cluster SPT-CL J0205–5829 currently has the highest spectroscopically confirmed redshift, z = 1.322, in the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. XMM-Newton observations measure a core-excluded temperature of T_X = 8.7^(+1.0)_(–0.8) keV producing a mass estimate that is consistent with the Sunyaev-Zel'dovich-derived mass. The combined SZ and X-ray mass estimate of M_(500) = (4.8 ± 0.8) × 10^(14) h^(–1)_(70) M_☉ makes it the most massive known SZ-selected galaxy cluster at z > 1.2 and the second most massive at z > 1. Using optical and infrared observations, we find that the brightest galaxies in SPT-CL J0205–5829 are already well evolved by the time the universe was <5 Gyr old, with stellar population ages ≳3 Gyr, and low rates of star formation (<0.5 M_☉ yr^(–1)). We find that, despite the high redshift and mass, the existence of SPT-CL J0205–5829 is not surprising given a flat ΛCDM cosmology with Gaussian initial perturbations. The a priori chance of finding a cluster of similar rarity (or rarer) in a survey the size of the 2500 deg^2 SPT-SZ survey is 69%.