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Title: Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies
Authors: García Bernete, I.
Ramos Almeida, C.
Alonso Herrero, A.
Ward, M. J.
Acosta Pulido, J. A.
Pereira Santaella, M.
Hernán Caballero, A.
Asensio Ramos, A.
González Martín, O.
Levenson, N. A.
Mateos, S.
Carrera, F. J.
Ricci, C.
Roche, P. F.
Márquez, I.
Packham, C.
Masegosa, J.
Fuller, L.
Keywords: Galaxies: active;Galaxies: nuclei;Galaxies: seyfert;Galaxies: photometry;Techniques: spectroscopic;Techniques: high angular resolution
Issue Date: 10-Apr-2019
Publisher: Oxford Academics: Oxford University Press
DOI: 10.1093/mnras/stz1003
Published version:
Citation: Monthly Notices of the Royal Astronomical Society 486(4): 4917–4935(2019)
Abstract: We characterize for the first time the torus properties of an ultra-hard X-ray (14–195 keV) volume-limited (DL < 40 Mpc) sample of 24 Seyfert (Sy) galaxies (BCS40 sample). The sample was selected from the Swift/BAT nine-month catalogue. We use high angular resolution nuclear infrared (IR) photometry and N-band spectroscopy, the CLUMPY torus models and a Bayesian tool to characterize the properties of the nuclear dust. In the case of the Sy1s, we estimate the accretion disc contribution to the subarcsecond resolution nuclear IR SEDs (∼0.4 arcsec) which is, on average, 46 ± 28, 23 ± 13, and 11 ± 5 per cent in the J, H, and K bands, respectively. This indicates that the accretion disc templates that assume a steep fall for longer wavelengths than 1 μm might underestimate its contribution to the near-IR emission. Using both optical (broad versus narrow lines) and X-ray (unabsorbed versus absorbed) classifications, we compare the global posterior distribution of the torus model parameters. We confirm that Sy2s have larger values of the torus covering factor (CT ∼ 0.95) than Sy1s (CT ∼ 0.65) in our volume-limited Seyfert sample. These findings are independent of whether we use an optical or X-ray classification. We find that the torus covering factor remains essentially constant within the errors in our luminosity range and there is no clear dependence with the Eddington ratio. Finally, we find tentative evidence that even an ultra-hard X-ray selection is missing a significant fraction of highly absorbed type 2 sources with very high covering factor tori.
Description: This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (
E-ISSN: 1365-2966
ISSN: 0035-8711
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