Please use this identifier to cite or link to this item: http://hdl.handle.net/2381/18776
 Title: An X-ray bright ERO hosting a type 2 QSO Authors: Severgnini, P.Caccianiga, A.Braito, V.Della Ceca RMaccacaro, T.Saracco, P.Braito, V.Akiyama, M.Carrera, F. J.Ceballos, M. T.Page, M. J.Watson, M. G. First Published: Jun-2006 Publisher: EDP Sciences for European Southern Observatory (ESO) Citation: Astronomy & Astrophysics, 2006, 451 (3), pp. 859-864 Abstract: We present the XMM-Newton and the optical-VLT spectra along with the optical and the near-infrared photometric data of one of the brightest X-ray ( $F_{2{-}10~\rm keV}\sim10^{-13}$ erg s-1 cm-2) extremely red objects ($R-K\ge5$) discovered so far. The source, XBS J0216-0435, belongs to the XMM-Newton Bright Serendipitous Survey and it has extreme X-ray-to-optical (~220) and X-ray-to-near-infrared (~60) flux ratios. Thanks to its brightness, the X-ray statistics are good enough for an accurate spectral analysis by which the presence of an X-ray obscured ( $N_{\rm H}>10^{22}$ cm-2) QSO ( $L_{2{-}10~\rm keV}=4\times10^{45}$ erg s-1) is determined. A statistically significant (~99%) excess around 2 keV in the observed-frame suggests the presence of an emission line. By assuming that this feature corresponds to the iron K$\alpha$ line at 6.4 keV, a first estimate of the redshift of the source is derived ( $z_{\rm X}\sim2$). The presence of a high redshift QSO2 has been finally confirmed through dedicated VLT optical spectroscopic observations ( $z_{\rm O}=1.985\pm0.002$). This result yields to an optical validation of a new X-ray Line Emitting Object (XLEO) for which the redshift has been firstly derived from the X-ray data. XBS J0216-0435 can be considered one of the few examples of X-ray obscured QSO2 at high redshift for which a detailed X-ray and optical spectral analysis has been possible. The spectral energy distribution from radio to X-rays is also presented. Finally from the near-infrared data the luminosity and the stellar mass of the host galaxy has been estimated finding a new example of the coexistence at high-z between massive galaxies and powerful QSOs. DOI Link: 10.1051/0004-6361:20053980 ISSN: 0004-6361 eISSN: 1432-0746 Links: http://hdl.handle.net/2381/18776http://www.aanda.org/articles/aa/abs/2006/21/aa3980-05/aa3980-05.html Version: Publisher Version Status: Peer-reviewed Type: Journal Article Rights: Copyright © 2006 ESO. Reproduced with permission from Astronomy & Astrophysics, © ESO. Appears in Collections: Published Articles, Dept. of Physics and Astronomy

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