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NuSTAR Observations of Water Megamaser AGNAims. 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 approx.10(exp 23) cm(exp -2); in particular, 79% are Compton-thick [NH is greater than 1.5 x 10(exp 24) cm(exp -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.
Document ID
20170003073
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Masini, A.
(Osservatorio Astronomico Bologna, Italy)
Comastri, A.
(Osservatorio Astronomico Bologna, Italy)
Balokvic, M.
(California Inst. of Tech. Pasadena, CA, United States)
Zaw, I.
(New York Univ. New York, NY, United States)
Puccetti, S.
(Istituto di Astrofisica Spaziale e Fisica Cosmica (INAF-IASF) Rome, Italy)
Ballantyne, D. R.
(Georgia Inst. of Tech. Atlanta, GA, United States)
Bauer, F. E.
(Space Science Inst. Boulder, CO, United States)
Boggs, S. E.
(California Univ. Berkeley, CA, United States)
Brandt, W. N.
(Pennsylvania State Univ. University Park, PA, United States)
Zhang, William W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
April 6, 2017
Publication Date
April 13, 2016
Publication Information
Publication: Astronomy & Astrophysics
Publisher: EDP Sciences
Volume: 589
ISSN: 0004-6361
e-ISSN: 1432-0746
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN40845
Distribution Limits
Public
Copyright
Other
Keywords
masers / galaxies: active / galaxies: Seyfert

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