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Published February 9, 2009 | Published
Journal Article Open

The XMM-Newton wide-field survey in the COSMOS field - The point-like X-ray source catalogue


Context. The COSMOS survey is a multiwavelength survey aimed to study the evolution of galaxies, AGN and large scale structures. Within this survey XMM-COSMOS a powerful tool to detect AGN and galaxy clusters. The XMM-COSMOS is a deep X-ray survey over the full 2 deg^2 of the COSMOS area. It consists of 55 XMM-Newton pointings for a total exposure of ~1.5 Ms with an average vignetting-corrected depth of 40 ks across the field of view and a sky coverage of 2.13 deg^2. Aims. We present the catalogue of point-like X-ray sources detected with the EPIC CCD cameras, the log N − log S relations and the X-ray colour–colour diagrams. Methods. The analysis was performed using the XMM-SAS data analysis package in the 0.5–2 keV, 2–10 keV and 5–10 keV energy bands. Source detection has been performed using a maximum likelihood technique especially designed for raster scan surveys. The completeness of the catalogue as well as log N − log S and source density maps have been calibrated using Monte Carlo simulations. Results. The catalogs contains a total of 1887 unique sources detected in at least one band with likelihood parameter det_ml > 10. The survey, which shows unprecedented homogeneity, has a flux limit of ~1.7×10^(−15) erg cm^(−2) s^(−1), ~9.3×10^(−15) erg cm^(−2) s^(−1) and ~1.3×10^(−14) erg cm^(−2) s^(−1) over 90% of the area (1.92 deg^2) in the 0.5–2 keV, 2–10 keV and 5–10 keV energy band, respectively. Thanks to the rather homogeneous exposure over a large area, the derived log N − log S relations are very well determined over the flux range sampled by XMM-COSMOS. These relations have been compared with XRB synthesis models, which reproduce the observations with an agreement of ~10% in the 5–10 keV and 2–10 keV band, while in the 0.5–2 keV band the agreement is of the order of ~20%. The hard X-ray colors confirmed that the majority of the extragalactic sources in a bright subsample are actually type I or type II AGN. About 20% of the sources have a X-ray luminosity typical of AGN (L_X > 10^(42) erg/s) although they do not show any clear signature of nuclear activity in the optical spectrum.

Additional Information

© ESO 2009. Received 13 August 2008. Accepted 14 January 2009. Part of this work was supported by the German Deutsche Forschungsgemeinschaft, DFG project number Ts 17/2–1.In Germany the XMM-Newton project is supported by the Bundesministerium für Wirtshaft und Techologie/Deutsches Zentrum für Luft und Raumfahrt and the Max-Planck society. N.C. and A.F. were partially supported from a NASA grant NNX07AV03G to UMBC. In Italy, the XMM-COSMOS project is supported by PRIN/MIUR under grant 2006-02-5203 and ASI-INAF grants I/023/05/00, I/088/06. Part of this work was supported by the German Deutsche Forschungsgemeinschaft,DFG Leibniz Prize (FKZ HA 1850/28-1). N.C. gratefully acknowledges Ezequiel Treister for providing his prediction of the XRB log N − log S. The entire COSMOS collaboration is gratefully acknowledged. N.C. acknowledges UNAM-Ensenada for the hospitality during his visit.

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Published - Cappelluti2009p1694Astron_Astrophys.pdf


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