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Title: An X-ray bright ERO hosting a type 2 QSO
Authors: Severgnini, P.
Caccianiga, A.
Braito, V.
Della Ceca R
Maccacaro, 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
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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