Clusters of galaxies in the COSMOS field

We present the results of a search for galaxy clusters in the first 36 XMM-Newton pointings on the COSMOS field. We reach a depth for a total cluster flux in the 0.5–2 keV band of 3× 10 ergs cm s, having one of the widest XMM-Newton contiguous raster surveys, covering an area of 2.1 square degrees. Cluster candidates are identified through a wavelet detection of extended X-ray emission. Verification of the cluster candidates is done based on a galaxy concentration analysis in redshift slices of thickness of 0.1–0.2 in redshift, using the multi-band photometric catalog of the COSMOS field and restricting the search to z < 1.3 and iAB < 25. We identify 72 clusters and derive their properties based on the X-ray cluster scaling relations. A statistical description of the survey in terms of the cumulative log(N > S)− log(S) distribution compares well with previous results, although yielding a somewhat higher number of clusters at similar fluxes. The X-ray luminosity function of COSMOS clusters matches well the results of nearby surveys, providing a comparably tight constraint on the faint end slope of α = 1.93±0.04. For the probed luminosity range of 8×10−2×10 ergs s, our survey is in agreement with and adds significantly to the existing data on the cluster luminosity function at high redshifts and implies no substantial evolution at these luminosities to z = 1.3.