Bibcode
Ramos Almeida, C.; Levenson, N. A.; Rodríguez Espinosa, J. M.; Alonso-Herrero, A.; Asensio Ramos, A.; Radomski, J. T.; Packham, C.; Fisher, R. S.; Telesco, C. M.
Bibliographical reference
The Astrophysical Journal, Volume 702, Issue 2, pp. 1127-1149 (2009).
Advertised on:
9
2009
Journal
Citations
166
Refereed citations
154
Description
We present subarcsecond resolution mid-infrared (mid-IR) photometry in
the wavelength range from 8 to 20 μm of 18 Seyfert galaxies,
reporting high spatial resolution nuclear fluxes for the entire sample.
We construct spectral energy distributions (SEDs) that the active
galactic nucleus (AGN) dominates, relatively uncontaminated by
starlight, adding near-IR measurements from the literature at similar
angular resolution. We find that the IR SEDs of intermediate-type
Seyferts are flatter and present higher 10 to 18 μm ratios than those
of Seyfert 2 galaxies. We fit the individual SEDs with clumpy dusty
torus models using the in-house-developed BayesClumpy tool. We find that
the clumpy models reproduce the high spatial resolution measurements.
Regardless of the Seyfert type, even with high spatial resolution data,
near- to mid-IR SED fitting poorly constrains the radial extent of the
torus. For the Seyfert 2 galaxies, we find that edge-on geometries are
more probable than face-on views, with a number of clouds along
equatorial rays of N 0 = 5-15. The 10 μm silicate feature
is generally modeled in shallow absorption. For the intermediate-type
Seyferts, N 0 and the inclination angle of the torus are
lower than those of the Seyfert 2 nuclei, with the silicate feature
appearing in weak emission or absent. The columns of material
responsible for the X-ray absorption are larger than those inferred from
the model fits for most of the galaxies, which is consistent with X-ray
absorbing gas being located within the dust sublimation radius, whereas
the mid-IR flux arises from an area farther from the accretion disk. The
fits yield both the bolometric luminosity of the intrinsic AGN and the
torus-integrated luminosity, from which we derive the reprocessing
efficiency of the torus. In the models, the outer radial extent of the
torus scales with the AGN luminosity, and we find the tori to be
confined to scales less than 5 pc.
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