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The relationship between Class I and Class II methanol masers at high angular resolution

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McCarthy, TP, Ellingsen, SP ORCID: 0000-0002-1363-5457, Voronkov, MA and Cimo, G 2018 , 'The relationship between Class I and Class II methanol masers at high angular resolution' , Monthly Notices of the Royal Astronomical Society, vol. 477, no. 1 , pp. 507-524 , doi: 10.1093/mnras/sty694.

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Abstract

We have used the Australia Telescope Compact Array (ATCA) to make the first high-resolution observations of a large sample of class I methanol masers in the 95-GHz (80-71A+) transition. The target sources consist of a statistically complete sample of 6.7-GHz class II methanol masers with an associated 95-GHz class I methanol maser, enabling a detailed study of the relationship between the two methanol maser classes at arcsecond angular resolution. These sources have been previously observed at high resolution in the 36- and 44-GHz transitions, allowing comparison between all three class I maser transitions. In total, 172 95-GHz maser components were detected across the 32 target sources. We find that at high resolution, when considering matched maser components, a 3:1 flux density ratio is observed between the 95- and 44-GHz components, consistent with a number of previous lower angular resolution studies. The 95-GHz maser components appear to be preferentially located closer to the driving sources and this may indicate that this transition is more strongly inverted nearby to background continuum sources. We do not observe an elevated association rate between 95-GHz maser emission and more evolved sources, as indicated by the presence of 12.2-GHz class II masers. We find that in the majority of cases where both class I and class II methanol emission is observed, some component of the class I emission is associated with a likely outflow candidate.

Item Type: Article
Authors/Creators:McCarthy, TP and Ellingsen, SP and Voronkov, MA and Cimo, G
Keywords: masers, radiolines, ISM
Journal or Publication Title: Monthly Notices of the Royal Astronomical Society
Publisher: Blackwell Publishing Ltd
ISSN: 0035-8711
DOI / ID Number: 10.1093/mnras/sty694
Copyright Information:

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2018 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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