Abstract
Aims. We study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser active galactic nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with the available physical quantities from VLBI mapping. Results. Most of the sources that we analyzed are heavily obscured, showing a column density in excess of ∼1023 cm-2; in particular, 79% are Compton-thick (NH > 1.5 × 1024 cm-2). When using column densities measured by NuSTAR with the assumption that the torus is the extension of the maser disk, and further assuming a reasonable density profile, we can predict the torus dimensions. They are found to be consistent with mid-IR interferometry parsec-scale observations of Circinus and NGC 1068. In this picture, the maser disk is intimately connected to the inner part of the torus. It is probably made of a large number of molecular clouds that connect the torus and the outer part of the accretion disk, giving rise to a thin disk rotating in most cases in Keplerian or sub-Keplerian motion. This toy model explains the established close connection between water megamaser emission and nuclear obscuration as a geometric effect.
| Original language | English (US) |
|---|---|
| Article number | A59 |
| Journal | Astronomy and Astrophysics |
| Volume | 589 |
| DOIs | |
| State | Published - May 1 2016 |
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Keywords
- galaxies: active
- galaxies: Seyfert
- masers
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
NuSTAR observations of water megamaser AGN. / Masini, A.; Comastri, A.; Baloković, M.; Zaw, Ingyin; Puccetti, S.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Gandhi, P.; Hailey, C. J.; Harrison, F. A.; Koss, M. J.; Madejski, G.; Ricci, C.; Rivers, E.; Stern, D.; Zhang, W. W.
In: Astronomy and Astrophysics, Vol. 589, A59, 01.05.2016.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - NuSTAR observations of water megamaser AGN
AU - Masini, A.
AU - Comastri, A.
AU - Baloković, M.
AU - Zaw, Ingyin
AU - Puccetti, S.
AU - Ballantyne, D. R.
AU - Bauer, F. E.
AU - Boggs, S. E.
AU - Brandt, W. N.
AU - Brightman, M.
AU - Christensen, F. E.
AU - Craig, W. W.
AU - Gandhi, P.
AU - Hailey, C. J.
AU - Harrison, F. A.
AU - Koss, M. J.
AU - Madejski, G.
AU - Ricci, C.
AU - Rivers, E.
AU - Stern, D.
AU - Zhang, W. W.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - Aims. We study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser active galactic nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with the available physical quantities from VLBI mapping. Results. Most of the sources that we analyzed are heavily obscured, showing a column density in excess of ∼1023 cm-2; in particular, 79% are Compton-thick (NH > 1.5 × 1024 cm-2). When using column densities measured by NuSTAR with the assumption that the torus is the extension of the maser disk, and further assuming a reasonable density profile, we can predict the torus dimensions. They are found to be consistent with mid-IR interferometry parsec-scale observations of Circinus and NGC 1068. In this picture, the maser disk is intimately connected to the inner part of the torus. It is probably made of a large number of molecular clouds that connect the torus and the outer part of the accretion disk, giving rise to a thin disk rotating in most cases in Keplerian or sub-Keplerian motion. This toy model explains the established close connection between water megamaser emission and nuclear obscuration as a geometric effect.
AB - Aims. We study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser active galactic nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with the available physical quantities from VLBI mapping. Results. Most of the sources that we analyzed are heavily obscured, showing a column density in excess of ∼1023 cm-2; in particular, 79% are Compton-thick (NH > 1.5 × 1024 cm-2). When using column densities measured by NuSTAR with the assumption that the torus is the extension of the maser disk, and further assuming a reasonable density profile, we can predict the torus dimensions. They are found to be consistent with mid-IR interferometry parsec-scale observations of Circinus and NGC 1068. In this picture, the maser disk is intimately connected to the inner part of the torus. It is probably made of a large number of molecular clouds that connect the torus and the outer part of the accretion disk, giving rise to a thin disk rotating in most cases in Keplerian or sub-Keplerian motion. This toy model explains the established close connection between water megamaser emission and nuclear obscuration as a geometric effect.
KW - galaxies: active
KW - galaxies: Seyfert
KW - masers
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U2 - 10.1051/0004-6361/201527689
DO - 10.1051/0004-6361/201527689
M3 - Article
VL - 589
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A59
ER -