Journal article · Preprint article
NuSTAR observations of water megamaser AGN
National Institute for Astrophysics1
Lawrence Livermore National Laboratory2
University of Southampton3
Columbia University4
Swiss Federal Institute of Technology Zurich5
SLAC National Accelerator Laboratory6
NASA Goddard Space Flight Center7
California Institute of Technology8
New York University Abu Dhabi9
Georgia Institute of Technology10
Pontificia Universidad Católica de Chile11
University of California at Berkeley12
Pennsylvania State University13
National Space Institute, Technical University of Denmark14
Astrophysics and Atmospheric Physics, National Space Institute, Technical University of Denmark15
...and 5 moreAims. 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 similar to 1023 cm-2; in particular, 79% are Compton-thick (NH > 1.5 x 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.
Language: | English |
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Publisher: | EDP Sciences |
Year: | 2016 |
Pages: | A59 |
ISSN: | 14320746 and 00046361 |
Types: | Journal article and Preprint article |
DOI: | 10.1051/0004-6361/201527689 |
ORCIDs: | Christensen, Finn Erland |