Discovery and Cosmological Implications of SPT-CL J2106-5844, the Most Massive Known Cluster at z &gt; 1
Creators: name: Foley, R. J.
name: Andersson, K.
name: Bazin, G.
name: de Haan, T.
name: Ruel, J.
name: Ade, P. A. R.
name: Aird, K. A.
name: Armstrong, R.
name: Ashby, M. L. N.
name: Bautz, M.
name: Benson, B. A.
name: Bleem, L. E.
name: Bonamente, M.
name: Brodwin, M.
name: Carlstrom, J. E.
name: Chang, C. L.
name: Clocchiatti, A.
name: Crawford, T. M.
name: Crites, A. T.
name: Desai, S.
name: Dobbs, M. A.
name: Dudley, J. P.
name: Fazio, G. G.
name: Forman, W. R.
name: Garmire, G.
name: George, E. M.
name: Gladders, M. D.
name: Gonzalez, A. H.
name: Halverson, N. W.
name: High, F. W.
name: Holder, G. P.
name: Holzapfel, W. L.
name: Hoover, S.
name: Hrubes, J. D.
name: Jones, C.
name: Joy, M.
name: Keisler, R.
name: Knox, L.
name: Lee, A. T.
name: Leitch, E. M.
name: Lueker, M.
name: Luong-Van, D.
name: Marrone, D. P.
name: McMahon, J. J.
name: Mehl, J.
name: Meyer, S. S.
name: Mohr, J. J.
name: Montroy, T. E.
name: Murray, S. S.
name: Padin, S.
name: Plagge, T.
name: Pryke, C.
name: Reichardt, C. L.
name: Rest, A.
name: Ruhl, J. E.
name: Saliwanchik, B. R.
name: Saro, A.
name: Schaffer, K. K.
name: Shaw, L.
name: Shirokoff, E.
name: Song, J.
name: Spieler, H. G.
name: Stalder, B.
name: Stanford, S. A.
name: Staniszewski, Z.
name: Stark, A. A.
name: Story, K.
name: Stubbs, C. W.
name: Vanderlinde, K.
name: Vieira, J. D.
name: Vikhlinin, A.
name: Williamson, R.
name: Zenteno, A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Using the South Pole Telescope (SPT), we have discovered the most massive known galaxy cluster at z &gt; 1, SPT-CL J2106-5844. In addition to producing a strong Sunyaev-Zel'dovich effect signal, this system is a luminous X-ray source and its numerous constituent galaxies display spatial and color clustering, all indicating the presence of a massive galaxy cluster. VLT and Magellan spectroscopy of 18 member galaxies shows that the cluster is at z = 1.132^+0.002_-0.003. Chandra observations obtained through a combined HRC-ACIS GTO program reveal an X-ray spectrum with an Fe K line redshifted by z = 1.18 +/- 0.03. These redshifts are consistent with galaxy colors in extensive optical, near-infrared, and mid-infrared imaging. SPT-CL J2106-5844 displays extreme X-ray properties for a cluster, having a core-excluded temperature of kT = 11.0^+2.6_-1.9 keV and a luminosity (within r_500) of L_X (0.5 - 2.0 keV) = (13.9 +/- 1.0) x 10^44 erg/s. The combined mass estimate from measurements of the Sunyaev-Zel'dovich effect and X-ray data is M_200 = (1.27 +/- 0.21) x 10^15 M_sun. The discovery of such a massive gravitationally collapsed system at high redshift provides an interesting laboratory for galaxy formation and evolution, and is a powerful probe of extreme perturbations of the primordial matter density field. We discuss the latter, determining that, under the assumption of LambdaCDM cosmology with only Gaussian perturbations, there is only a 7% chance of finding a galaxy cluster similar to SPT-CL J2106-5844 in the 2500 deg^2 SPT survey region, and that only one such galaxy cluster is expected in the entire sky.
description: 10 pages, submitted to ApJ