Netzer, Hagai and Lutz, Dieter and Schweitzer, Mario and Contursi, Alessandra and Sturm, Eckhard and Tacconi, Linda J. and Veilleux, Sylvain and Kim, D.-C. and Rupke, David and Baker, Andrew J. and Dasyra, Kalliopi and Mazzarella, Joseph and Lord, Steven (2007) Spitzer Quasar and ULIRG Evolution Study (QUEST). II. The Spectral Energy Distributions of Palomar-Green Quasars. Astrophysical Journal, 666 (2). pp. 806-816. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20091201-145405293
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This is the second paper studying the QSOs in the Spitzer QUEST sample. Previously we presented new PAH measurements and argued that most of the observed far-infrared (FIR) radiation is due to star-forming activity. Here we present spectral energy distributions (SEDs) by supplementing our data with optical, NIR, and FIR observations. We define two subgroups, of "weak FIR" and "strong FIR" QSOs, and a third group of FIR nondetections. Assuming a starburst origin for the FIR, we obtain "intrinsic" active galactic nucleus (AGN) SEDs by subtracting a starburst template from the mean SEDs. The resulting SEDs are remarkably similar for all groups. They show three distinct peaks corresponding to two silicate emission features and a 3 μm bump, which we interpret as the signature of the hottest AGN dust. They also display drops beyond ~20 μm that we interpret as the signature of the minimum temperature (~200 K) dust. This component must be optically thin to explain the silicate emission and the slope of the long-wavelength continuum. We discuss the merits of an alternative model in which most of the FIR emission is due to AGN heating. Such models are unlikely to explain the properties of our QSOs, but they cannot be ruled out for more luminous objects. We also find correlations between the luminosity at 5100 Å and two infrared starburst indicators: L(60 μm) and L(PAH 7.7 μm). The correlation of L(5100 Å) with L(60 μm) can be used to measure the relative growth rates and lifetimes of the black hole and the new stars.
|Additional Information:||© 2007 The American Astronomical Society. Received 2007 March 7; accepted 2007 June 4. We thank Todd Boroson for kindly allowing us to use his optical data for PG quasars. We thank Amiel Sternberg for discussions and comments on the manuscript. Funding for this work has been provided by the Israel Science Foundation grant 232/03. S. V., D. S. R., and D. C. K. were supported in part by NASA contract 1263752 issued by the Jet Propulsion Laboratory, California Institute of Technology. H. N. acknowledges a Humboldt Foundation prize and thanks the host institution, MPE Garching, where most of this work was performed.|
|Subject Keywords:||galaxies : active; galaxies : starburst; infrared : galaxies; quasars : emission lines|
|Official Citation:||Spitzer Quasar and ULIRG Evolution Study (QUEST). II. The Spectral Energy Distributions of Palomar-Green Quasars Hagai Netzer, Dieter Lutz, Mario Schweitzer, Alessandra Contursi, Eckhard Sturm, Linda J. Tacconi, Sylvain Veilleux, D.-C. Kim, David Rupke, Andrew J. Baker, Kalliopi Dasyra, Joseph Mazzarella, and Steven Lord 2007 ApJ 666 806-816 doi: 10.1086/520716|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||23 Dec 2009 04:00|
|Last Modified:||26 Dec 2012 11:35|
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