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84-GHz methanol masers, their relationship to 36-GHz methanol masers, and their molecular environments
Citation
Breen, SL and Contreras, Y and Dawson, JR and Ellingsen, SP and Voronkov, MA and McCarthy, TP, 84-GHz methanol masers, their relationship to 36-GHz methanol masers, and their molecular environments, Monthly Notices of the Royal Astronomical Society, 484, (4) pp. 5072-5093. ISSN 0035-8711 (2019) [Refereed Article]
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Copyright Statement
Copyright 2019 The Authors. This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Abstract
We present observations of the 36-GHz (4−1 → 30 E) and 84-GHz (5−1 → 40 E) class I methanol maser transitions towards a sample of 94 known class I sites. These observations resulted in 93 and 92 detections in the 84- and 36-GHz transitions. While the majority of the 36-GHz sources have been previously reported, many of the sites are observed in the 84-GHz transition for the first time. The near-simultaneous observations of the two transitions revealed strikingly similar spectral profiles and a mean and median 36- to 84-GHz integrated flux density ratio of 2.6 and 1.4. Alongside the 36- and 84-GHz observations, we included rare class II methanol masers at 37.7, 38.3, 38.5, 86.6, and 86.9 GHz, a number of recombination lines, and thermal molecular transitions. We detect one new site of 86.6- and 86.9-GHz methanol masers, as well as six maser candidates in one or more of 37.7-, 38.3-, 38.5-, 86.6-, and 86.9-GHz methanol maser transitions. We detect a relatively higher rate of HC3N compared to that reported by MALT90 (once the respective detection limits were taken into account), who targeted dense dust clumps, suggesting that the class I methanol maser targets incorporate a relatively higher number of warm protostellar sources. We further find that there are similar relationships between the integrated flux density of both class I transitions with the integrated intensity of HC3N, HNC, HCO+, HNC, SiO, and H13CO+. We suggest that this indicates that the integrated flux densities of the 36- and 84-GHz transitions are closely linked to the available gas volume.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | masers–stars:formation–ISM:molecules–radiolines:ISM |
| Research Division: | Physical Sciences |
| Research Group: | Astronomical sciences |
| Research Field: | Cosmology and extragalactic astronomy |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the physical sciences |
| UTAS Author: | Ellingsen, SP (Professor Simon Ellingsen) |
| UTAS Author: | McCarthy, TP (Dr Tiege McCarthy) |
| ID Code: | 131092 |
| Year Published: | 2019 |
| Funding Support: | Australian Research Council (DP180101061) |
| Web of Science® Times Cited: | 8 |
| Deposited By: | Mathematics and Physics |
| Deposited On: | 2019-02-28 |
| Last Modified: | 2020-05-20 |
| Downloads: | 31 View Download Statistics |
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