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XMM-Newton observation of the Lockman Hole II. Spectral analysis | V. Mainieri
; J. Bergeron
; G. Hasinger
; I. Lehmann
; P. Rosati
; M. Schmidt
; G. Szokoly
; R. Della Ceca
; | Date: |
8 Jul 2002 | Journal: | Astron.Astrophys. 393 (2002) 425-438 | Subject: | astro-ph | Affiliation: | 1, 2), J. Bergeron , G. Hasinger (4, 5), I. Lehmann , P. Rosati , M. Schmidt , G. Szokoly (4, 5) and R. Della Ceca ( Universita` degli Studi Roma Tre, European Southern Observatory, Institut d’Astrophysique de Paris, Max-Planck-Institut f&uum | Abstract: | We present the results of the X-ray spectral analysis of the first deep X-ray survey with the XMM-Newton observatory during Performance Verification. We restrict the analysis to the sample of 98 sources with more than 70 net counts (flux limit in the [0.5-7] keV band of 1.6 10^{-15} erg cm^{-2} s^{-1}) of which 61 have redshift identification. We find no correlation between the spectral index Gamma and the intrinsic absorption column density N_H and, for both the Type-1 and Type-2 AGN populations, we obtain ~2. The progressive hardening of the mean X-ray source spectrum with decreasing flux is essentially due to an increase in intrinsic absorption. The marked separation between the two AGN populations in several diagnostics diagrams, involving X-ray colour, X-ray flux, optical/near IR colour and optical brightness, is also a consequence of different absorption column densities and enables the classification of optically faint obscured AGN. About 27% of the subsample with R-K’ colour are EROs (R-K>5) and most of these 18 X-ray selected EROs contain anobscured AGN as revealed by their high X-ray-to-optical/near IR flux ratios. There are six sources in our sample with L_X[0.5-10]>10^44 erg s^{-1} and log(N_H)>10^22 cm^{-2}: which are likely Type-2 QSOs and we thus derive a density of ~69 objects of this class per square degree. | Source: | arXiv, astro-ph/0207166 | Services: | Forum | Review | PDF | Favorites |
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