Scintillation in the Circinus Galaxy H2O Megamasers

We present observations of the 22 GHz water vapor megamasers in the Circinus galaxy made with the Tidbinbilla 70 m telescope. These observations confirm the rapid variability seen earlier by Greenhill et al. We show that this rapid variability can be explained by interstellar scintillation, based on...

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Bibliographic Details
Published in:The Astronomical journal 2005-03, Vol.129 (3), p.1231-1236
Main Authors: McCallum, Jamie N, Ellingsen, Simon P, Jauncey, David L, Lovell, James E. J, Greenhill, Lincoln J
Format: Article
Language:English
Online Access:Get full text
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Summary:We present observations of the 22 GHz water vapor megamasers in the Circinus galaxy made with the Tidbinbilla 70 m telescope. These observations confirm the rapid variability seen earlier by Greenhill et al. We show that this rapid variability can be explained by interstellar scintillation, based on what is now known of the interstellar scintillation seen in a significant number of flat-spectrum active galactic nuclei. The observed variability cannot be fully described by a simple model of either weak or diffractive scintillation.
ISSN:1538-3881
0004-6256
1538-3881
DOI:10.1086/427399