Investigating the sensitivity of observed spectral energy distributions to clumpy torus properties in Seyfert galaxies

Ramos Almeida, C.; Alonso-Herrero, A.; Levenson, N. A.; Asensio Ramos, A.; Rodríguez Espinosa, J. M.; González-Martín, O.; Packham, C.; Martínez, M.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 439, Issue 4, p.3847-3859

Advertised on:
3
2014
Number of authors
8
IAC number of authors
4
Citations
39
Refereed citations
34
Description
We present nuclear spectral energy distributions (SEDs) from 1 to 18 μm of a small sample of nearby, nearly face-on and undisturbed Seyfert galaxies without prominent nuclear dust lanes. These nuclear SEDs probe the central ˜35 pc of the galaxies, on average, and include photometric and spectroscopic infrared (IR) data. We use these SEDs, the clumpy torus models of Nenkova et al. and a Bayesian approach to study the sensitivity of different IR wavelengths to the torus parameters. We find that high angular resolution 8-13 μm spectroscopy alone reliably constrains the number of clumps and their optical depth (N0 and τV). On the other hand, we need a combination of mid- and near-IR subarcsecond resolution photometry to constrain torus width and inclination, as well as the radial distribution of the clouds (σ, i and q). For flat radial profiles (q = 0, 1), it is possible to constrain the extent of the mid-IR-emitting dust within the torus (Y) when N-band spectroscopy is available, in addition to near-IR photometry. Finally, by fitting different combinations of average and individual Seyfert 1 and Seyfert 2 data, we find that, in general, for undisturbed, nearly face-on Seyferts without prominent nuclear dust lanes, the minimum combination of data necessary to reliably constrain all the torus parameters is J+K+M-band photometry + N-band spectroscopy.
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