Astronomy & Astrophysics

Free access article

Issue		A&A Volume 487, Number 2, August IV 2008
Page(s)		L33 - L36
Section		Letters
DOI		10.1051/0004-6361:200810255
Published online		01 July 2008

A&A 487, L33-L36 (2008)
DOI: 10.1051/0004-6361:200810255

Letter

2XMM J083026+524133: the most X-ray luminous cluster at redshift 1

G. Lamer, M. Hoeft, J. Kohnert, A. Schwope, and J. Storm

Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: glamer@aip.de

Received 25 May 2008 / Accepted 23 June 2008

Abstract
Aims. In the distant universe X-ray luminous clusters of galaxies are rare objects. Large area surveys are therefore needed to probe the high luminosity end of the cluster population at redshifts $z \ga 1$ .
Methods. We correlated extended X-ray sources from the second XMM-Newton source catalogue (2XMM) with the SDSS in order to identify new clusters of galaxies. Distant cluster candidates in empty SDSS fields were imaged in the r- and z-bands with the Large Binocular Telescope. We extracted the X-ray spectra of the cluster candidates and fitted thermal plasma models to the data.
Results. We determined the redshift 0.99 $\pm$ 0.03 for 2XMM J083026.2+524133 from its X-ray spectrum. With a bolometric luminosity of 1.8 $\times$ $10^~{\rm erg\,s^}$ this is the most X-ray luminous cluster at redshifts $z \geq 1$ . We measured a gas temperature of 8.2 $\pm$ 0.9 keV and estimate a cluster mass M₅₀₀ = 5.6 $\times$ $10^~M_{\odot}$ . The optical imaging revealed a rich cluster of galaxies.

Key words: galaxies: clusters: individual: 2XMM J083026.2+524133 -- X-rays: galaxies: clusters

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