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Abstract

We report the detection of class I methanol maser at the 36.2 GHz transition toward the nearby starburst galaxy Maffei 2 with the Karl G. Jansky Very Large Array. Observations of the 36.2 GHz transition at two epochs separated by ∼4 yr show consistencies in both the spatial distribution and flux density of the methanol emission in this transition. Similar to the detections in other nearby starbursts the class I methanol masers sites are offset by a few hundred pc from the center of the galaxy and appear to be associated with the bar edges of Maffei 2. Narrow spectral features with line widths of a few km s−1 are detected, supporting the hypothesis that they are masing. Compared to other nearby galaxies with the detections in the 36.2 GHz methanol maser transition, the maser detected in Maffei 2 has about an order of magnitude higher isotropic luminosity, and thus represents the first confirmed detection of class I methanol megamasers. The spatial distribution of the 36.2 GHz maser spot clusters may trace the rotational gas flow of the galactic bar, providing direct evidence that the class I methanol maser is related to shocks induced by galactic bar rotation. A tentative detection in the 6.7 GHz class II methanol maser (at a 5σ level) is also reported. This is comparable in luminosity to some of the 6.7 GHz maser sources detected in Galactic star-forming regions. The 6.7 GHz methanol emission appears to be associated with star formation activity in a smaller volume, rather than related to the larger-scale galactic activities.

Item Type:	Article
Authors/Creators:	Chen, X and Yang, T and Ellingsen, SP and McCarthy, TP and Ren, Z-Y
Keywords:	astrophysical masers, extragalactic astronomy, circumgalactic medium, barred spiral galaxies, interstellar masers, megamasers
Journal or Publication Title:	The Astrophysical Journal
Publisher:	Institute of Physics Publishing, Inc
ISSN:	1538-4357
DOI / ID Number:	10.3847/1538-4357/ac3f32
Copyright Information:	Copyright 2022 The Author(s)Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/
Related URLs:	Google Scholar: Ellingsen, SP UTAS Profile: Ellingsen, SP
Item Statistics:	View statistics for this item

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