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 Hernan-Caballero, A. and Perez-Fournon, I. and Serjeant, S. and Lonsdale, C. and Oliver, S. 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. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1111/j.1365-2966.2008.13119.x

Abstract

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 chi(2)-minimization; the model, however, can be a multicomponent comprising a stellar and a starburst component, whenever necessary. Models with low equatorial optical depth, tau(9.7), were allowed as well as 'traditional' models with tau(9.7) >= 1.0, corresponding to A(V) >= 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 tau(9.7) 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, M-Dust, and IR luminosity, L-IR, integrated in the wavelength range between 1 and 1000 mu m, do not show significant variations with redshift, once the observational biases are taken into account. Objects with 70-mu m 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
Uncontrolled keywords: galaxies : active; quasars : general; galaxies : starburst; infrared : general
Subjects: Q Science > QB Astronomy
Divisions: Faculties > Science Technology and Medical Studies > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Suzanne Duffy
Date Deposited: 23 Feb 2009 14:17
Last Modified: 23 Feb 2009 14:17
Resource URI: http://kar.kent.ac.uk/id/eprint/15145 (The current URI for this page, for reference purposes)
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