The XMM-Newton Wide-Field Survey in the COSMOS field (XMM-COSMOS): demography and multiwavelength properties of obscured and unobscured luminous AGN
Creators: name: Brusa, M.
name: Civano, F.
name: Comastri, A.
name: Miyaji, T.
name: Salvato, M.
name: Zamorani, G.
name: Cappelluti, N.
name: Fiore, F.
name: Hasinger, G.
name: Mainieri, V.
name: Merloni, A.
name: Bongiorno, A.
name: Capak, P.
name: Elvis, M.
name: Gilli, R.
name: Hao, H.
name: Jahnke, K.
name: Koekemoer, A. M.
name: Ilbert, O.
name: Floc'h, E. Le
name: Lusso, E.
name: Mignoli, M.
name: Schinnerer, E.
name: Silverman, J. D.
name: Treister, E.
name: Trump, J. D.
name: Vignali, C.
name: Zamojski, M.
name: Aldcroft, T.
name: Aussel, H.
name: Bardelli, S.
name: Bolzonella, M.
name: Cappi, A.
name: Caputi, K.
name: Contini, T.
name: Finoguenov, A.
name: Fruscione, A.
name: Garilli, B.
name: Impey, C. D.
name: Iovino, A.
name: Iwasawa, K.
name: Kampczyk, P.
name: Kartaltepe, J.
name: Kneib, J. P.
name: Knobel, C.
name: Kovac, K.
name: Lamareille, F.
name: Leborgne, J-F.
name: Brun, V. Le
name: Fevre, O. Le
name: Lilly, S. J.
name: Maier, C.
name: McCracken, H. J.
name: Pello, R.
name: Peng, Y-J
name: Perez-Montero, E.
name: de Ravel, L.
name: Sanders, D.
name: Scodeggio, M.
name: Scoville, N. Z.
name: Tanaka, M.
name: Taniguchi, Y.
name: Tasca, L.
name: de la Torre, S.
name: Tresse, L.
name: Vergani, D.
name: Zucca, E.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report the final optical identifications of the medium-depth (~60 ksec), contiguous (2 deg^2) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ~800 X-ray sources down to limiting fluxes of ~5x10^{-16}, ~3x10^{-15}, and ~7x10^{-15} erg/cm2/s in the 0.5-2 keV, 2-10 keV and 5-10 keV bands, respectively. The work is complemented by an extensive collection of multi-wavelength data from 24 micron to UV, available from the COSMOS survey, for each of the X-ray sources, including spectroscopic redshifts for ~50% of the sample, and high-quality photometric redshifts for the rest. The XMM and multiwavelength flux limits are well matched: 1760 (98%) of the X-ray sources have optical counterparts, 1711 (~95%) have IRAC counterparts, and 1394 (~78%) have MIPS 24micron detections. Thanks to the redshift completeness (almost 100%) we were able to constrain the high-luminosity tail of the X-ray luminosity function confirming that the peak of the number density of logL_X&gt;44.5 AGN is at z~2. Spectroscopically-identified obscured and unobscured AGN, as well as normal and starforming galaxies, present well-defined optical and infrared properties. We devised a robust method to identify a sample of ~150 high redshift (z&gt;1), obscured AGN candidates for which optical spectroscopy is not available. We were able to determine that the fraction of the obscured AGN population at the highest (L_X&gt;10^{44} erg s^{-1}) X-ray luminosity is ~15-30% when selection effects are taken into account, providing an important observational constraint for X-ray background synthesis. We studied in detail the optical spectrum and the overall spectral energy distribution of a prototypical Type 2 QSO, caught in a stage transitioning from being starburst dominated to AGN dominated, which was possible to isolate only thanks to the combination of X-ray and infrared observations.
description: ApJ, in press. 59 pages, 14 figures, 2 Tables. A few typos corrected and a reference added. Table 2 is also available at http://www.mpe.mpg.de/XMMCosmos/xmm53_release ; a version of the paper in ApJ format (27 pages) is available at http://www.mpe.mpg.de/XMMCosmos/xmm53_release/brusa_xmmcosmos_optid.pdf