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Paper: Variable Water Maser Emission from the CMZ of the Circinus Galaxy and NGC 4945
Volume: 528, New Horizons in Galactic Center Astronomy and Beyond
Page: 131
Authors: Hagiwara, Y.; Horiuchi, S.; Edwards, P. G.
Abstract: The results of single-dish monitoring of H2O maser emission using the Tidbinbilla 70 m telescope and imaging with ALMA towards the central molecular zone (CMZ) in the Circinus galaxy and NGC 4945 active galaxies are reported. Intense 22 GHz H2O maser emission has been well studied in the galaxies, with the maser in the Circinus galaxy being extremely variable. The maser in NGC 4945 also shows long-term variability over 4 years. Water masers in the 321 GHz transition were detected in both galaxies by ALMA, although they remain unresolved at ∼0.3” resolution in our observations. Although we have only two epochs of ALMA data, the single-dish monitoring data seem to indicate that trends of the long-term variability between the 22 and 321 GHz transitions are similar for NGC 4945, which suggests that molecular gas in similar regions might be related for maser amplification against background sources.
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