SPT-CL J0205–5829: a z = 1.32 evolved massive galaxy cluster in the South Pole Telescope Sunyaev-Zel'dovich effect survey

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(-0.8)(+1.0) 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) x 10(14)h(70)(-1) M-circle dot 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 greater than or similar to 3 Gyr, and low rates of star formation (< 0.5 M-circle dot yr(-1)). We find that, despite the high redshift and mass, the existence of SPT-CL J0205-5829 is not surprising given a flat Lambda CDM 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%.