Bibcode
Hatziminaoglou, E.; Fritz, J.; Franceschini, A.; Afonso-Luis, A.; Hernán-Caballero, A.; Pérez-Fournon, I.; Serjeant, S.; Lonsdale, C.; Oliver, S.; Rowan-Robinson, M.; Shupe, D.; Smith, H. E.; Surace, J.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 386, Issue 3, pp. 1252-1264.
Advertised on:
5
2008
Citations
68
Refereed citations
65
Description
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.
Related projects
Formation and Evolution of Galaxies: Observations in Infrared and other Wavelengths
This IAC research group carries out several extragalactic projects in different spectral ranges, using space as well as ground-based telescopes, to study the cosmological evolution of galaxies and the origin of nuclear activity in active galaxies. The group is a member of the international consortium which built the SPIRE instrument for the
Ismael
Pérez Fournon