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Detection of 36GHz Class I methanol maser emission toward NGC 4945


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McCarthy, TP ORCID: 0000-0001-9525-7981, Ellingsen, SP ORCID: 0000-0002-1363-5457, Chen, X, Breen, SL, Voronkov, MA and Qiao, H-h 2017 , 'Detection of 36GHz Class I methanol maser emission toward NGC 4945' , Astrophysical Journal, vol. 846, no. 2 , pp. 1-5 , doi: 10.3847/1538-4357/aa872c.

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We have searched for emission from the 36.2 GHz (4-1 → 30E) methanol transition toward NGC 4945, using the Australia Telescope Compact Array. 36.2 GHz methanol emission was detected offset southeast from the Galactic nucleus. The methanol emission is narrow, with a line width −1 and a luminosity five orders of magnitude higher than Galactic class I masers from the same transition. These characteristics combined the with physical separation from the strong central thermal emission suggests that the methanol emission is a maser. This emission is a factor of ∼90 more luminous than the widespread emission detected from the Milky Way central molecular zone. This is the fourth detection of extragalactic class I emission and the third detection of extragalactic 36.2 GHz maser emission. These extragalactic class I methanol masers do not appear to be simply highly luminous variants of Galactic class I emission and instead appear to trace large-scale regions of low-velocity shocks in molecular gas, which may precede, or be associated with, the early stages of large-scale star formation.

Item Type: Article
Authors/Creators:McCarthy, TP and Ellingsen, SP and Chen, X and Breen, SL and Voronkov, MA and Qiao, H-h
Keywords: masers, galaxies: individual (NGC 4945), galaxies: starburst, radio lines: ISM
Journal or Publication Title: Astrophysical Journal
Publisher: Univ Chicago Press
ISSN: 0004-637X
DOI / ID Number: 10.3847/1538-4357/aa872c
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Copyright 2017 The American Astronomical Society

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