Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/18890
 Title: The XMM-Newton bright serendipitous survey - Identification and optical spectral properties Authors: Caccianiga, A.Severgnini, P.Della Ceca RMaccacaro, T.Cocchia, F.Barcons, X.Carrera, F. J.Matute, I.McMahon, R. G.Page, M. J.Pietsch, W.Sbarufatti, B.Schwope, A.Tedds, J. A.Watson, M. G. First Published: 1-Jan-2008 Publisher: EDP Sciences for European Southern Observatory (ESO) Citation: Astronomy & Astrophysics, 2008, 477 (3), pp. 735-U53 Abstract: Aims.We present the optical classification and redshift of 348 X-ray selected sources from the XMM-Newton Bright Serendipitous Survey (XBS), which contains a total of 400 objects (identification level = 87%). About 240 are new identifications. In particular, we discuss in detail the classification criteria adopted for the active galactic nuclei (AGNs) population. Methods.By means of systematic spectroscopic campaigns using various telescopes and through the literature search, we have collected an optical spectrum for the large majority of the sources in the XBS survey and applied a well-defined classification "flow chart". Results.We find that the AGNs represent the most numerous population at the flux limit of the XBS survey (~10-13 erg cm-2 s-1) constituting 80% of the XBS sources selected in the 0.5-4.5 keV energy band and 95% of the "hard" (4.5-7.5 keV) selected objects. Galactic sources populate the 0.5-4.5 keV sample significantly (17%) and only marginally (3%) the 4.5-7.5 keV sample. The remaining sources in both samples are clusters/groups of galaxies and normal galaxies (i.e. probably not powered by an AGN). Furthermore, the percentage of type 2 AGNs (i.e. optically absorbed AGNs with $A_{\rm V}>2$ mag) dramatically increases going from the 0.5-4.5 keV sample ( $f=N_{\rm AGN 2}/N_{\rm AGN}=7$%) to the 4.5-7.5 keV sample (f=32%). We finally propose two simple diagnostic plots that can be easily used to obtain the spectral classification for relatively low-redshift AGNs even if the quality of the spectrum is not good. DOI Link: 10.1051/0004-6361:20078568 ISSN: 0004-6361 Links: http://hdl.handle.net/2381/18890http://www.aanda.org/articles/aa/abs/2008/03/aa8568-07/aa8568-07.html Version: Publisher Version Status: Peer-reviewed Type: Journal Article Rights: Copyright © 2008 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO. Appears in Collections: Published Articles, Dept. of Physics and Astronomy

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