Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies

García-Bernete, I; Ramos Almeida, C; Alonso-Herrero, A; Ward, MJ; Acosta-Pulido, JA; Pereira-Santaella, M; Hernán-Caballero, A; Asensio Ramos, A; González-Martín, O; Levenson, NA; Mateos, S; Carrera, FJ; Ricci, C; Roche, P; Marquez, I; Packham, C; Masegosa, J; Fuller, L

doi:10.1093/mnras/stz1003

Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies

García-Bernete, I; Ramos Almeida, C; Alonso-Herrero, A; Ward, MJ; Acosta-Pulido, JA; Pereira-Santaella, M; Hernán-Caballero, A; Asensio Ramos, A; González-Martín, O; Levenson, NA; Mateos, S; Carrera, FJ; Ricci, C; Roche, P; Marquez, I; Packham, C; Masegosa, J; Fuller, L

Authors

I García-Bernete

C Ramos Almeida

A Alonso-Herrero

Professor Martin Ward martin.ward@durham.ac.uk
External Examiner (PGR)

JA Acosta-Pulido

M Pereira-Santaella

A Hernán-Caballero

A Asensio Ramos

O González-Martín

NA Levenson

S Mateos

FJ Carrera

C Ricci

P Roche

I Marquez

C Packham

J Masegosa

L Fuller

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.

Citation

García-Bernete, I., Ramos Almeida, C., Alonso-Herrero, A., Ward, M., Acosta-Pulido, J., Pereira-Santaella, M., …Fuller, L. (2019). Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies. Monthly Notices of the Royal Astronomical Society, 486(4), 4917-4935. https://doi.org/10.1093/mnras/stz1003

Journal Article Type	Article
Acceptance Date	Apr 4, 2019
Online Publication Date	Apr 10, 2019
Publication Date	Jul 31, 2019
Deposit Date	Jul 16, 2019
Publicly Available Date	Jul 16, 2019
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	486
Issue	4
Pages	4917-4935
DOI	https://doi.org/10.1093/mnras/stz1003