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AGN accretion disk physics using H2O megamasers

Published online by Cambridge University Press:  16 July 2018

Dominic Pesce ,
James Braatz ,
James Condon ,
Feng Gao ,
Christian Henkel ,
Violette Impellizzeri ,
Eugenia Litzinger ,
K. Y. Lo  and
Mark Reid
Dominic Pesce
Affiliation:
Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904, USA National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
James Braatz
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
James Condon
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
Feng Gao
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA Shanghai Astronomical Observatory, Chinese Academy of Sciences, 200030 Shanghai, China
Christian Henkel
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany Astronomy Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
Violette Impellizzeri
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA Joint Alma Office, Alsonso de Cordova 3107, Vitacura, Santiago, Chile
Eugenia Litzinger
Affiliation:
Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Fischer-Str. 31, D-97074 Würzburg, Germany Dr. Remeis Sternwarte & ECAP, Universität Erlangen-Nürnberg, Sternwartstrasse 7, D-96049 Bamberg, Germany
K. Y. Lo
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
Mark Reid
Affiliation:
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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Abstract

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Many accretion disks surrounding supermassive black holes in nearby AGN are observed to host 22 GHz water maser activity. We have analyzed single-dish 22 GHz spectra taken with the GBT to identify 32 such “Keplerian disk systems,” which we used to investigate maser excitation and explore the possibility of disk reverberation. Our results do not support a spiral shock model for population inversion in these disks, and we find that any reverberating signal propagating radially outwards from the AGN must constitute <10% of the total observed maser variability. Additionally, we have used ALMA to begin exploring the variety of sub-mm water megamasers that are also predicted, and in the case of the 321 GHz transition found, to be present in these accretion disks. By observing multiple masing transitions within a single system, we can better constrain the physical conditions (e.g., gas temperature and density) in the accretion disk.

Keywords

accretion disksmasersgalaxies: active
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S336: Astrophysical Masers: Unlocking the Mysteries of the Universe , September 2017 , pp. 125 - 128
Copyright
Copyright © International Astronomical Union 2018 

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