The XMM-LSS survey

Abstract

We present five newly found galaxy clusters at from the XMM Large-Scale Structure Survey (XMM-LSS). All five objects are extended X-ray sources in the XMM images. For three of them we have sufficient spectroscopically confirmed member galaxies that an estimate of the velocity dispersion is possible: XLSSC 001 at and km s-1, XLSSC 002 at and km s-1 and XLSSC 003 at and km s-1. These three clusters have X-ray bolometric luminosities erg s-1 and temperatures keV, and consequently are less massive than previously known clusters at similar redshifts, but nevertheless they follow the low redshift scaling relations between and , within the limits of the measurement errors. One of the clusters, XLSSC 004, is detected independently as an overdensity of galaxies of a colour that matches the redshift of the central galaxy , although it cannot unambiguously be confirmed by the spectroscopic observations alone. The highest redshift candidate cluster pertaining to this paper, XLSSC 005, is most likely a double cluster complex at a redshift around unity, associated with an extended X-ray source with probable substructure.