2004A&A...423...75V

We present five newly found galaxy clusters at z>0.6 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 z=0.613 and σ_V=867⁺⁸⁰_–60km/s, XLSSC 002 at z=0.772 and σ_V=524⁺²⁶⁷_–116km/s and XLSSC 003 at z=0.839 and σ_V=780⁺¹³⁷_–75km/s. These three clusters have X-ray bolometric luminosities L_X∼1-3x10⁴⁴erg/s and temperatures 2-4keV, and consequently are less massive than previously known clusters at similar redshifts, but nevertheless they follow the low redshift scaling relations between L_X, T and σ_v, within the limits of the measurement errors. One of the clusters, XLSSC 004, is detected independently as an overdensity of galaxies of a colour R-z'=1.4 that matches the redshift of the central galaxy z=0.87, 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.