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Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars

Richards, Gordon T. and Lacy, Mark and Storrie-Lombardi, Lisa J. and Hall, Patrick B. and Gallagher, S. C. and Hines, Dean C. and Fan, Xiaohui and Papovich, Casey and Vanden Berk, Daniel E. and Trammell, George B. and Schneider, Donald P. and Vestergaard, Marianne and York, Donald G. and Jester, Sebastian and Anderson, Scott F. and Budavári, Tamás and Szalay, Alexander S. (2006) Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars. Astrophysical Journal Supplement Series, 166 (2). pp. 470-497. ISSN 0067-0049.

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We present an analysis of the mid-infrared (MIR) and optical properties of type 1 (broad-line) quasars detected by the Spitzer Space Telescope. The MIR color-redshift relation is characterized to z ~ 3, with predictions to z = 7. We demonstrate how combining MIR and optical colors can yield even more efficient selection of active galactic nuclei (AGNs) than MIR or optical colors alone. Composite spectral energy distributions (SEDs) are constructed for 259 quasars with both Sloan Digital Sky Survey and Spitzer photometry, supplemented by near-IR, GALEX, VLA, and ROSAT data, where available. We discuss how the spectral diversity of quasars influences the determination of bolometric luminosities and accretion rates; assuming the mean SED can lead to errors as large as 50% for individual quasars when inferring a bolometric luminosity from an optical luminosity. Finally, we show that careful consideration of the shape of the mean quasar SED and its redshift dependence leads to a lower estimate of the fraction of reddened/obscured AGNs missed by optical surveys as compared to estimates derived from a single mean MIR to optical flux ratio.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lacy, Mark0000-0002-3032-1783
Storrie-Lombardi, Lisa J.0000-0002-5987-5210
Hines, Dean C.0000-0003-4653-6161
Fan, Xiaohui0000-0003-3310-0131
Papovich, Casey0000-0001-7503-8482
Additional Information:© 2006 American Astronomical Society. Received 2006 January 24; accepted 2006 May 26. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, Cambridge University, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPA), the Max-Planck-Institute for Astrophysics (MPIA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. This work is based on observations made with the Spitzer Space Telescope, operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with NASA. Support was provided by NASA through JPL. G. T. R. further acknowledges support from a Gordon and Betty Moore Fellowship in data intensive sciences. X. F. and M. V. acknowledge support from NSF grant AST-0307384.We thank an anonymous referee, especially for helping with figure presentation and also Eilat Glikman for making her IR quasar composite spectrum available in advance of publication.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:catalogs; galaxies: active; infrared: galaxies; quasars: general; radio continuum: galaxies; surveys; ultraviolet: galaxies; X-rays: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20110719-112238177
Persistent URL:
Official Citation:Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars Gordon T. Richards et al. 2006 ApJS 166 470
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24462
Deposited By: Jason Perez
Deposited On:19 Jul 2011 20:12
Last Modified:09 Mar 2020 13:19

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