We report the spectroscopic confirmation of SPT-CL J0546-5345 at (z) = 1.067. To date this is the most distant cluster to be spectroscopically confirmed from the 2008 South Pole Telescope (SPT) catalog, and indeed the first z > 1 cluster discovered by the Sunyaev-Zel'dovich Effect (SZE). We identify 21 secure spectroscopic members within 0.9 Mpc of the SPT cluster position, 18 of which are quiescent, early-type galaxies. From these quiescent galaxies we obtain a velocity dispersion of 1179-167+232 km s -1, ranking SPT-CL J0546-5345 as the most dynamically massive cluster yet discovered at z > 1. Assuming that SPT-CL J0546-5345 is virialized, this implies a dynamical mass of M200 = 1.0-0.4 +0.6×1015M⊙, in agreement with the X-ray and SZE mass measurements. Combining masses from several independent measures leads to a best-estimate mass of M200 = (7.95 ± 0.92) × 1014M⊙. The spectroscopic confirmation of SPT-CL J0546-5345, discovered in the wide-angle, mass-selected SPT cluster survey, marks the onset of the high-redshift SZE-selected galaxy cluster era.
- Galaxies: Evolution
- Galaxies: clusters: individual (SPT-CL J0546-5345)
- Galaxies: distances and redshifts