Volume 534, October 2011
|Number of page(s)||13|
|Section||Catalogs and data|
|Published online||19 October 2011|
The 2XMMi/SDSS Galaxy Cluster Survey
I. The first cluster sample and X-ray luminosity–temperature relation⋆
Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
2 National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt
Received: 16 June 2011
Accepted: 22 August 2011
We present a catalogue of X-ray selected galaxy clusters and groups as a first release of the 2XMMi/SDSS Galaxy Cluster Survey. The survey is a search for galaxy clusters detected serendipitously in observations with XMM-Newton in the footprint of the Sloan Digital Sky Survey (SDSS). The main aims of the survey are to identify new X-ray galaxy clusters, investigate their X-ray scaling relations, identify distant cluster candidates, and study the correlation of the X-ray and optical properties. In this paper, we describe the basic strategy to identify and characterize the X-ray cluster candidates that currently comprise 1180 objects selected from the second XMM-Newton serendipitous source catalogue (2XMMi-DR3). Cross-correlation of the initial catalogue with recently published optically selected SDSS galaxy cluster catalogues yields photometric redshifts for 275 objects. Of these, 182 clusters have at least one member with a spectroscopic redshift from existing public data (SDSS-DR8). We developed an automated method to reprocess the XMM-Newton X-ray observations, determine the optimum source extraction radius, generate source and background spectra, and derive the temperatures and luminosities of the optically confirmed clusters. Here we present the X-ray properties of the first cluster sample, which comprises 175 clusters, among which 139 objects are new X-ray discoveries while the others were previously known as X-ray sources. For each cluster, the catalogue provides: two identifiers, coordinates, temperature, flux [0.5−2] keV, luminosity [0.5−2] keV extracted from an optimum aperture, bolometric luminosity L500, total mass M500, radius R500, and the optical properties of the counterpart. The first cluster sample from the survey covers a wide range of redshifts from 0.09 to 0.61, bolometric luminosities L500 = 1.9 × 1042−1.2 × 1045 erg s-1, and masses M500 = 2.3 × 1013−4.9 × 1014 M⊙. We extend the relation between the X-ray bolometric luminosity L500 and the X-ray temperature towards significantly lower T and L and still find that the slope of the linear L − T relation is consistent with values published for high luminosities.
Key words: X-rays: galaxies: clusters / galaxies: clusters: general / surveys / catalogs
Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/534/A120
© ESO, 2011
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