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Properties of dusty tori in active galactic nuclei – I. The case of SWIRE/SDSS quasars

Hatziminaoglou, E. and Fritz, J. and Franceschini, A. and Afonso-Luis, A. and Hernán-Caballero, A. and Pérez-Fournon, I. and Serjeant, S. and Lonsdale, C. and Oliver, S. A. and Rowan-Robinson, M. and Shupe, D. and Smith, H. E. and Surace, J. (2008) Properties of dusty tori in active galactic nuclei – I. The case of SWIRE/SDSS quasars. Monthly Notices of the Royal Astronomical Society, 386 (3). pp. 1252-1264. ISSN 0035-8711.

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We derive the properties of dusty tori in active galactic nuclei from the comparison of observed spectral energy distributions (SEDs) of SDSS quasars and a precomputed grid of torus models. The observed SEDs comprise SDSS photometry, Two-Micron All-Sky Survey J, H and K data, whenever available, and mid-infrared (mid-IR) data from the Spitzer Wide-area InfraRed Extragalactic Survey. The adopted model is that of Fritz, Franceschini & Hatziminaoglou. The fit is performed by standard χ2 -minimization; the model, however, can be a multicomponent comprising a stellar and a starburst component, whenever necessary. Models with low equatorial optical depth, τ9.7, were allowed as well as 'traditional' models with τ9.7≥ 1.0 , corresponding to AV≥ 22 and the results were compared. Fits using high optical depth tori models only produced dust more compactly distributed than in the configuration where all τ9.7 models were permitted. Tori with decreasing dust density with the distance from the centre were favoured while there was no clear preference for models with or without angular variation of the dust density. The computed outer radii of the tori are of some tens of parsecs large but can reach, in a few cases, a few hundreds of parsecs. The mass of dust, MDust, and IR luminosity, LIR, integrated in the wavelength range between 1 and 1000 μm, do not show significant variations with redshift, once the observational biases are taken into account. Objects with 70-μm detections, representing 25 per cent of the sample, are studied separately and the starburst contribution (whenever present) to the IR luminosity can reach, in the most extreme but very few cases, 80 per cent.

Item Type:Article
Related URLs:
URLURL TypeDescription
Serjeant, S.0000-0002-0517-7943
Lonsdale, C.0000-0003-0898-406X
Shupe, D.0000-0003-4401-0430
Surace, J.0000-0001-7291-0087
Additional Information:© 2008 The Authors. Journal compilation © 2008 RAS. Accepted 2008 February 15. Received 2008 February 8; in original form 2007 December 18. This work is based on observations made 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, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through an award issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the US Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS Web site is This publication makes use of data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Centre/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work was supported in part by the Spanish Ministerio de Educación y Ciencia (Grants ESP2004-06870-C02-01 and ESP2007-65812-C02-02). This work makes extensive use of TOPCAT ( a Virtual Observatory tool developed by M. Taylor.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Participating InstitutionsUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Japanese MonbukagakushoUNSPECIFIED
Max Planck SocietyUNSPECIFIED
Ministerio de Educación y Ciencia (MEC)ESP2004-06870-C02-01
Ministerio de Educación y Ciencia (MEC)ESP2007-65812-C02-02
Subject Keywords:active galaxies; quasars; starburst galaxies; infrared astronomy
Issue or Number:3
Record Number:CaltechAUTHORS:HATmnras08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11290
Deposited By: Tony Diaz
Deposited On:06 Aug 2008 00:04
Last Modified:30 Sep 2020 18:11

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