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Spitzer Quasar and ULIRG Evolution Study (QUEST). I. The Origin of the Far-Infrared Continuum of QSOs

Schweitzer, M. and Lutz, D. and Sturm, E. and Contursi, A. and Tacconi, L. J. and Lehnert, M. D. and Dasyra, K. M. and Genzel, R. and Veilleux, S. and Rupke, D. and Kim, D. -C. and Baker, A. J. and Netzer, H. and Sternberg, A. and Mazzarella, J. and Lord, S. (2006) Spitzer Quasar and ULIRG Evolution Study (QUEST). I. The Origin of the Far-Infrared Continuum of QSOs. Astrophysical Journal, 649 (1). pp. 79-90. ISSN 0004-637X.

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This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z ≲ 0.3, we derive luminosities of diagnostic lines ([Ne II] 12.8 μm, [Ne V] 14.3 μm, [O IV] 25.9 μm) and emission features (PAH 7.7 μm emission, which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60 μm. We detect star-formation-related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources that lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [Ne II]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30% but likely most of the far-infrared luminosity (~10^(10)-10^(12) L_☉) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low-excitation [Ne II]) offer additional support for the starburst origin of far-infrared emission.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lutz, D.0000-0003-0291-9582
Tacconi, L. J.0000-0002-1485-9401
Lehnert, M. D.0000-0003-1939-5885
Genzel, R.0000-0002-2767-9653
Veilleux, S.0000-0002-3158-6820
Mazzarella, J.0000-0002-8204-8619
Additional Information:© 2006 American Astronomical Society. Received 2006 March 16; accepted 2006 May 24. We thank Aprajita Verma, Natascha Förster Schreiber, and Helene Roussel for help with comparison starburst data.We are grateful for comments by the referee. This work is based on observations carried out 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 was provided by NASA through contract 1263752 (S. V.) issued by JPL/Caltech. H. N. acknowledges a Humboldt Foundation prize and thanks the host institution,MPEGarching, where thiswork has been done. A. J. B. acknowledges support from the National Radio Astronomy Observatory,which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation.
Funding AgencyGrant Number
Humboldt FoundationUNSPECIFIED
National Radio Astronomy ObservatoryUNSPECIFIED
Subject Keywords:galaxies: active; galaxies: starburst; infrared: galaxies; quasars: emission lines
Issue or Number:1
Record Number:CaltechAUTHORS:20110719-112317777
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Official Citation:Spitzer Quasar and ULIRG Evolution Study (QUEST). I. The Origin of the Far-Infrared Continuum of QSOs M. Schweitzer et al. 2006 ApJ 649 79
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24463
Deposited By: Jason Perez
Deposited On:19 Jul 2011 20:02
Last Modified:17 Jul 2019 22:03

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