Polletta, M. and Tajer, M. and Maraschi, L. and Trinchieri, G. and Lonsdale, C. J. and Chiappetti, L. and Andreon, S. and Pierre, M. and Le Fèvre, O. and Zamorani, G. and Maccagni, D. and Garcet, O. and Surdej, J. and Franceschini, A. and Alloin, D. and Shupe, D. L. and Surace, J. A. and Fang, F. and Rowan-Robinson, M. and Smith, H. E. and Tresse, L. (2007) Spectral Energy Distributions of Hard X-Ray Selected Active Galactic Nuclei in the XMM-Newton Medium Deep Survey. Astrophysical Journal, 663 (1). pp. 81-102. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20101018-111256502
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We present the SEDs of a hard X-ray selected sample containing 136 sources with F_(2-10 keV) > 10^(-14) erg cm^(-2) s^(-1); 132 are AGNs. The sources are detected in a 1 deg^2 area of the XMM-Newton Medium Deep Survey where optical data from the VVDS and CFHTLS and infrared data from the SWIRE survey are available. Based on a SED fitting technique we derive photometric redshifts with σ(1 + z) = 0.11 and 6% of outliers and identify AGN signatures in 83% of the objects. This fraction is higher than derived when a spectroscopic classification is available. The remaining 17^(+9)_(-6)% of AGNs show star-forming galaxy SEDs (SF class). The sources with AGN signatures are divided in two classes, AGN1 (33^(+6)_(-1)%) and AGN2 (50^(+6)_(-11)%). The AGN1 and AGN2 classes include sources whose SEDs are fitted by type 1 and type 2 AGN templates, respectively. On average, AGN1s show soft X-ray spectra, consistent with being unabsorbed, while AGN2s and SFs show hard X-ray spectra, consistent with being absorbed. The analysis of the average SEDs as a function of X-ray luminosity shows a reddening of the infrared SEDs, consistent with a decreasing contribution from the host galaxy at higher luminosities. The AGNs in the SF classes are likely obscured in the mid-infrared, as suggested by their low L_(3-20 μm)/L^(corr)_(0.5-10 keV) ratios. We confirm the previously found correlation for AGNs between the radio luminosity and the X-ray and the mid-infrared luminosities. The X-ray-radio correlation can be used to identify heavily absorbed AGNs. However, the estimated radio fluxes for the missing AGN population responsible for the bulk of the background at E > 10 keV are too faint to be detected even in the deepest current radio surveys.
|Additional Information:||© 2007 American Astronomical Society. Received 2006 November 15; accepted 2007 March 2. M. P. thanks L. Silva for providing help in producing templates with GRASIL, B. Schulz for providing the PG quasars’ ISO PHT-S spectra, H. McCracken for useful suggestions, and S. Berta, S. Hönig, and F. Owen for stimulating discussions. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through an award issued by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. The INAF members of the team acknowledge financial contribution from contract ASI INAF I /023/05/0. M. T. acknowledges financial support from MIUR Cofin 2004-023189-005. O.G. and J. S. acknowledge support from the ESA PRODEX Programme ‘‘XMM-LSS’’ and from the Belgian Federal Science Policy Office. This research makes use of the NASA/ IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHTand CEA/ DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Facilities: XMM-Newton, Spitzer.|
|Subject Keywords:||galaxies: active; infrared: galaxies; quasars: general; X-rays: galaxies|
|Official Citation:||M. Polletta et al 2007 ApJ 663 81 doi: 10.1086/518113|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||26 Oct 2010 18:30|
|Last Modified:||26 Dec 2012 12:32|
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