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Title: NuSTAR observations of water megamaser AGN

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 inmore » Keplerian or sub-Keplerian motion. This toy model explains the established close connection between water megamaser emission and nuclear obscuration as a geometric effect.« less

Authors:
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Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA)
OSTI Identifier:
1313957
Report Number(s):
SLAC-PUB-16785
Journal ID: ISSN 0004-6361; arXiv:1602.03185
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 589; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; masers; galaxies:active; galaxies: Seyfert

Citation Formats

Masini, A., Comastri, A., Baloković, M., Zaw, I., 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., and Zhang, W. W. NuSTAR observations of water megamaser AGN. United States: N. p., 2016. Web. doi:10.1051/0004-6361/201527689.
Masini, A., Comastri, A., Baloković, M., Zaw, I., 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. NuSTAR observations of water megamaser AGN. United States. https://doi.org/10.1051/0004-6361/201527689
Masini, A., Comastri, A., Baloković, M., Zaw, I., 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., and Zhang, W. W. 2016. "NuSTAR observations of water megamaser AGN". United States. https://doi.org/10.1051/0004-6361/201527689. https://www.osti.gov/servlets/purl/1313957.
@article{osti_1313957,
title = {NuSTAR observations of water megamaser AGN},
author = {Masini, A. and Comastri, A. and Baloković, M. and Zaw, I. and Puccetti, S. and Ballantyne, D. R. and Bauer, F. E. and Boggs, S. E. and Brandt, W. N. and Brightman, M. and Christensen, F. E. and Craig, W. W. and Gandhi, P. and Hailey, C. J. and Harrison, F. A. and Koss, M. J. and Madejski, G. and Ricci, C. and Rivers, E. and Stern, D. and Zhang, W. W.},
abstractNote = {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.},
doi = {10.1051/0004-6361/201527689},
url = {https://www.osti.gov/biblio/1313957}, journal = {Astronomy and Astrophysics},
issn = {0004-6361},
number = ,
volume = 589,
place = {United States},
year = {Wed Apr 13 00:00:00 EDT 2016},
month = {Wed Apr 13 00:00:00 EDT 2016}
}