# Discovery and Cosmological Implications of SPT-CL J2106-5844, the Most Massive Known Cluster at z \> 1

Source: [Discovery and Cosmological Implications of SPT-CL J2106-5844, the Most Massive Known Cluster at z \> 1](<https://www.sota2.com/research/paper/68fa2f921e209131ce86d50f>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T17:39:09.170Z

Authors: R. J. Foley, K. Andersson, G. Bazin, T. de Haan, J. Ruel, P. A. R. Ade, K. A. Aird, R. Armstrong, M. L. N. Ashby, M. Bautz, B. A. Benson, L. E. Bleem, M. Bonamente, M. Brodwin, J. E. Carlstrom, C. L. Chang, A. Clocchiatti, T. M. Crawford, A. T. Crites, S. Desai, M. A. Dobbs, J. P. Dudley, G. G. Fazio, W. R. Forman, G. Garmire, E. M. George, M. D. Gladders, A. H. Gonzalez, N. W. Halverson, F. W. High, G. P. Holder, W. L. Holzapfel, S. Hoover, J. D. Hrubes, C. Jones, M. Joy, R. Keisler, L. Knox, A. T. Lee, E. M. Leitch, M. Lueker, D. Luong-Van, D. P. Marrone, J. J. McMahon, J. Mehl, S. S. Meyer, J. J. Mohr, T. E. Montroy, S. S. Murray, S. Padin, T. Plagge, C. Pryke, C. L. Reichardt, A. Rest, J. E. Ruhl, B. R. Saliwanchik, A. Saro, K. K. Schaffer, L. Shaw, E. Shirokoff, J. Song, H. G. Spieler, B. Stalder, S. A. Stanford, Z. Staniszewski, A. A. Stark, K. Story, C. W. Stubbs, K. Vanderlinde, J. D. Vieira, A. Vikhlinin, R. Williamson, A. Zenteno

Published: 2011-01-06T20:23:55.000Z

## Abstract

Using the South Pole Telescope (SPT), we have discovered the most massive known galaxy cluster at z \> 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.

## Recorded benchmark results

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/1101.1286>)

[PDF](<https://arxiv.org/pdf/1101.1286.pdf>)