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A mid-infrared statistical investigation of clumpy torus model predictions

A mid-infrared statistical investigation of clumpy torus model predictions
A mid-infrared statistical investigation of clumpy torus model predictions
We present new calculations of the Clumpy AGN Tori in a 3D geometry (CAT3D) clumpy torus models, which now include a more physical dust sublimation model as well as active galactic nucleus (AGN) anisotropic emission. These new models allow graphite grains to persist at temperatures higher than the silicate dust sublimation temperature. This produces stronger near-infrared emission and bluer mid-infrared (MIR) spectral slopes. We make a statistical comparison of the CAT3D model MIR predictions with a compilation of sub-arcsecond resolution ground-based MIR spectroscopy of 52 nearby Seyfert galaxies (median distance of 36 Mpc) and 10 quasars. We focus on the AGN MIR spectral index αMIR and the strength of the 9.7 μm silicate feature SSil. As with other clumpy torus models, the new CAT3D models do not reproduce the Seyfert galaxies with deep silicate absorption (SSil < −1). Excluding those, we conclude that the new CAT3D models are in better agreement with the observed αMIR and SSil of Seyfert galaxies and quasars. We find that Seyfert 2 are reproduced with models with low photon escape probabilities, while the quasars and the Seyfert 1–1.5 require generally models with higher photon escape probabilities. Quasars and Seyfert 1–1.5 tend to show steeper radial cloud distributions and fewer clouds along an equatorial line of sight than Seyfert 2. Introducing AGN anisotropic emission besides the more physical dust sublimation models alleviates the problem of requiring inverted radial cloud distributions (i.e. more clouds towards the outer parts of the torus) to explain the MIR spectral indices of type 2 Seyferts.
0035-8711
2578-2598
Gonzalez-Garcia, J.
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Alonso-Herrero, A.
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Hoenig, S.F.
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Hernan-Caballero, A.
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Ramos Almeida, C.
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Levenson, N.A.
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Roche, P.F.
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Gonzalez-Martin, O.
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Packham, C.
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Kishimoto, M.
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Gonzalez-Garcia, J.
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Alonso-Herrero, A.
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Hoenig, S.F.
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Hernan-Caballero, A.
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Ramos Almeida, C.
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Levenson, N.A.
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Roche, P.F.
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Gonzalez-Martin, O.
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Packham, C.
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Kishimoto, M.
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Gonzalez-Garcia, J., Alonso-Herrero, A., Hoenig, S.F., Hernan-Caballero, A., Ramos Almeida, C., Levenson, N.A., Roche, P.F., Gonzalez-Martin, O., Packham, C. and Kishimoto, M. (2017) A mid-infrared statistical investigation of clumpy torus model predictions. Monthly Notices of the Royal Astronomical Society, 470 (3), 2578-2598. (doi:10.1093/mnras/stx1361).

Record type: Article

Abstract

We present new calculations of the Clumpy AGN Tori in a 3D geometry (CAT3D) clumpy torus models, which now include a more physical dust sublimation model as well as active galactic nucleus (AGN) anisotropic emission. These new models allow graphite grains to persist at temperatures higher than the silicate dust sublimation temperature. This produces stronger near-infrared emission and bluer mid-infrared (MIR) spectral slopes. We make a statistical comparison of the CAT3D model MIR predictions with a compilation of sub-arcsecond resolution ground-based MIR spectroscopy of 52 nearby Seyfert galaxies (median distance of 36 Mpc) and 10 quasars. We focus on the AGN MIR spectral index αMIR and the strength of the 9.7 μm silicate feature SSil. As with other clumpy torus models, the new CAT3D models do not reproduce the Seyfert galaxies with deep silicate absorption (SSil < −1). Excluding those, we conclude that the new CAT3D models are in better agreement with the observed αMIR and SSil of Seyfert galaxies and quasars. We find that Seyfert 2 are reproduced with models with low photon escape probabilities, while the quasars and the Seyfert 1–1.5 require generally models with higher photon escape probabilities. Quasars and Seyfert 1–1.5 tend to show steeper radial cloud distributions and fewer clouds along an equatorial line of sight than Seyfert 2. Introducing AGN anisotropic emission besides the more physical dust sublimation models alleviates the problem of requiring inverted radial cloud distributions (i.e. more clouds towards the outer parts of the torus) to explain the MIR spectral indices of type 2 Seyferts.

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A mid-infrared statistical investigation of clumpy torus - Accepted Manuscript
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Accepted/In Press date: 31 May 2017
e-pub ahead of print date: 3 June 2017
Published date: September 2017

Identifiers

Local EPrints ID: 413109
URI: http://eprints.soton.ac.uk/id/eprint/413109
ISSN: 0035-8711
PURE UUID: e0e3ffae-6fb6-4e95-8ba4-52f48e90b4a1

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Date deposited: 15 Aug 2017 16:30
Last modified: 21 Nov 2021 08:01

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Contributors

Author: J. Gonzalez-Garcia
Author: A. Alonso-Herrero
Author: S.F. Hoenig
Author: A. Hernan-Caballero
Author: C. Ramos Almeida
Author: N.A. Levenson
Author: P.F. Roche
Author: O. Gonzalez-Martin
Author: C. Packham
Author: M. Kishimoto

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