Bibcode
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.; Marquez, I.; Packham, C.; Masegosa, J.; Fuller, L.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 4, p.4917-4935
Advertised on:
7
2019
Citations
37
Refereed citations
34
Description
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.
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