Cosmology with XMM galaxy clusters: the X-CLASS/GROND catalogue and photometric redshifts

<p class="MsoNormal">The <i>XMM</i> Cluster Archive Super Survey (X-CLASS) is a serendipitously detected X-ray-selected sample of 845 galaxy clusters based on 2774 XMM archival observations and covering an approximately 90 deg² spread across the high-Galactic latitude (|<i>b</i>| &gt; 20^◦) sky. The primary goal of this survey is to produce a well-selected sample of galaxy clusters on which cosmological analyses can be performed. This paper presents the photometric redshift follow[1]up of a high signal-to-noise ratio subset of 265 of these clusters with declination δ &lt; +20^◦ with Gamma-Ray Burst Optical and Near-Infrared Detector (GROND), a 7-channel (<i>grizJHK</i>) simultaneous imager on the MPG 2.2-m telescope at the ESO La Silla Observatory. We use a newly developed technique based on the red sequence colour–redshift relation, enhanced with information coming from the X-ray detection to provide photometric redshifts for this sample. We determine photometric redshifts for 232 clusters, finding a median redshift of z = 0.39 with an accuracy of Δz = 0.02(1 + z) when compared to a sample of 76 spectroscopically confirmed clusters. We also compute X-ray luminosities for the entire sample and find a median bolometric luminosity of 7.2 × 10⁴³ erg s⁻¹ and a median temperature of 2.9 keV. We compare our results to those of the <i>XMM</i>-XCS and <i>XMM</i>-XXL surveys, finding good agreement in both samples. The X-CLASS catalogue is available online at http://xmm-lss.in2p3.fr:8080/l4sdb/.

Перевод пока недоступен