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The X-ray to optical-UV luminosity ratio of X-ray selected type 1 AGN in XMM-COSMOS

Lusso, E. and Comastri, A. and Vignali, C. and Zamorani, G. and Brusa, M. and Gilli, R. and Iwasawa, K. and Salvato, M. and Civano, F. and Elvis, M. and Merloni, A. and Bongiorno, A. and Trump, J. R. and Koekemoer, A. M. and Schinnerer, E. and Le Floc'h, E. and Cappelluti, N. and Jahnke, K. and Sargent, M. and Silverman, J. and Mainieri, V. and Fiore, F. and Bolzonella, M. and Le Fèvre, O. and Garilli, B. and Iovino, A. and Kneib, J. P. and Lamareille, F. and Lilly, S. and Mignoli, M. and Scodeggio, M. and Vergani, D. (2010) The X-ray to optical-UV luminosity ratio of X-ray selected type 1 AGN in XMM-COSMOS. Astronomy and Astrophysics, 512 . A34. ISSN 0004-6361.

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We present a study of the X-ray to optical properties of a sample of 545 X-ray selected type 1 AGN, from the XMM-COSMOS survey, over a wide range of redshifts (0.04 < z < 4.25) and X-ray luminosities (40.6 ≤ Log L_([2-10] keV) ≤ 45.3). About 60% of them are spectroscopically identified type 1 AGN, while the others have a reliable photometric redshift and are classified as type 1 AGN on the basis of their multi-band Spectral Energy Distributions. We discuss the relationship between UV and X-ray luminosity, as parameterized by the α_(ox) spectral slope, and its dependence on redshift and luminosity. We compare our findings with previous investigations of optically selected broad-line AGN (mostly from SDSS). A highly significant correlation between α_(ox) and L_(2500 Å) is found, in agreement with previous investigations of optically selected samples. We calculate bolometric corrections, k_(bol), for the whole sample using hard X-ray luminosities (L_([2-10] keV)), and the Eddington ratios for a subsample of 150 objects for which black hole mass estimates are available. We confirm the trend of increasing bolometric correction with increasing Eddington ratio as proposed in previous works. A tight correlation is found between α_(ox) and k_(bol), which can be used to estimate accurate bolometric corrections using only optical and X-ray data. We find a significant correlation between α_(ox) and Eddington ratio, in which the ratio between X-ray and optical flux decreases with increasing Eddington ratio.

Item Type:Article
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URLURL TypeDescription
Comastri, A.0000-0003-3451-9970
Iwasawa, K.0000-0002-4923-3281
Schinnerer, E.0000-0002-3933-7677
Additional Information:© 2010 ESO. Received: 15 September 2009; accepted: 4 January 2010. In Italy, the XMM-COSMOS project is supported by PRIN/MIUR under grant 2006-02-5203, ASI-INAF grants I/023/05/00, I/088/06 and ASI/COFIS/WP3110 I/026/07/0. In Germany the XMM-Newton project is supported by the Bundesministerium für Wirtshaft und Techologie/Deutsches Zentrum für Luft und Raumfahrt and the Max-Planck society. The entire COSMOS collaboration is gratefully acknowledged.
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:galaxies: active; Galaxy: evolution; quasars: general; methods: statistical
Record Number:CaltechAUTHORS:20100607-120917341
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Official Citation:The X-ray to optical-UV luminosity ratio of X-ray selected type 1 AGN in XMM-COSMOS E. Lusso, A. Comastri, C. Vignali, G. Zamorani, M. Brusa, R. Gilli, K. Iwasawa, M. Salvato, F. Civano, M. Elvis, A. Merloni, A. Bongiorno, J. R. Trump, A. M. Koekemoer, E. Schinnerer, E. Le Floc'h, N. Cappelluti, K. Jahnke, M. Sargent, J. Silverman, V. Mainieri, F. Fiore, M. Bolzonella, O. Le Fèvre, B. Garilli, A. Iovino, J. P. Kneib, F. Lamareille, S. Lilly, M. Mignoli, M. Scodeggio and D. Vergani A&A 512 A34 (2010) DOI: 10.1051/0004-6361/200913298
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18584
Deposited By: Jason Perez
Deposited On:07 Jun 2010 20:24
Last Modified:31 Oct 2017 21:54

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