SZ and X-ray combined analysis of a distant galaxy cluster, RX J2228+2037

¹ CESR–CNRS, 9 Av. du Colonel Roche, 31028 Toulouse, France
² Astronomical Institute, Tohoku University, Sendai 980-8578, Japan
³ SAp–CEA, L'Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France
⁴ Department of Astrophysical Sciences, Princeton, NJ 08544, USA
⁵ National Astronomical Observatory, Mitaka Tokyo 181-8588, Japan
⁶ Nobeyama Radio Observatory, Minamimaki Nagano 384-1305, Japan
⁷ Max-Planck Institut Für Extraterrische Physik, Garching 85740, Germany

Corresponding author: E. Pointecouteau, etienne@astr.tohoku.ac.jp

Received: 14 December 2001
Accepted: 4 March 2002

Abstract

We have performed a combined analysis of X-ray and Sunyaev-Zel'dovich data in the direction of the distant galaxy cluster, RX J2228+2037. Fitting a β-model to the high-resolution HRI data gives  kpc and . The dependency of the Sunyaev-Zel'dovich effect with respect to the gas temperature allows us, through the additional use of the 21 GHz data of the cluster, to determine  keV. Extrapolating the gas density profile out to the virial radius ( Mpc), we derived a gas mass of . Within the hypothesis of hydrostatic equilibrium, the corresponding extrapolated total mass for this source is: , which corresponds to a gas fraction of . Our results on the temperature and on the cluster mass classify RX J2228+2037 among the distant, hot and very massive galaxy clusters. Our work highlights the power of the association of galaxy cluster mapping observations in X-ray and the SZ effect to derive the cluster's physical properties, even without X-ray spectroscopy.