Letter to the Editor

XMM-Newton detection of two clusters of galaxies with strong SPT Sunyaev-Zel'dovich effect signatures^*

¹ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching, Germany e-mail: rsuhada@mpe.mpg.de
² University of Illinois, Department of Astronomy, 1002 West Green St, Urbana, IL 61801, USA
³ Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
⁴ Department of Physics, University of California, Berkeley, CA 94720, USA
⁵ Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
⁶ Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munich, Germany
⁷ Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
⁸ University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
⁹ Laboratoire AIM, IRFU/Service d'Astrophysique – CEA/DSM – CNRS – Université Paris Diderot, Bât. 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹⁰ MKI, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Received: 15 March 2010
Accepted: 14 April 2010

Abstract

We report on the discovery of two galaxy clusters, SPT-CL J2332-5358 and SPT-CL J2342-5411, in X-rays. These clusters were also independently detected through their Sunyaev-Zel'dovich effect by the South Pole Telescope, and in the optical band by the Southern Cosmology Survey. They are thus the first clusters detected under survey conditions by all major cluster search approaches. The X-ray detection is made within the frame of the XMM-BCS cluster survey utilizing a novel XMM-Newton mosaic-mode of observations. The present study makes the first scientific use of this operation mode. We estimate the X-ray spectroscopic temperature of SPT-CL J2332-5358  (at redshift z = 0.32) to be T = 9.3 keV, implying a high mass, M₅₀₀ = 8.8 ± 3.8 × 10¹⁴ . For SPT-CL J2342-5411, at z = 1.08, the available X-ray data do not allow us to directly estimate the temperature with good confidence. However, using our measured luminosity and scaling relations we estimate that T = 4.5 ± 1.3 keV and M₅₀₀ = 1.9 ± 0.8 × 10¹⁴ . We find a good agreement between the X-ray masses and those estimated from the Sunyaev-Zel'dovich effect.