Jordan, CH, Walsh, AJ, Lowe, V, Voronkov, MA, Ellingsen, SP, Breen, SL, Purcell, CR, Barnes, PJ, Burton, MG, Cunningham, MR, Hill, T, Jackson, JM, Longmore, SN, Peretto, N and Urquhart, JS (2015) MALT-45: a 7 mm survey of the southern Galaxy - I. Techniques and spectral line data. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 448 (3). pp. 2344-2361. ISSN 0035-8711

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Abstract

We present the first results from the MALT-45 (Millimetre Astronomer's Legacy Team-45 GHz) Galactic Plane survey. We have observed 5 square degrees (l = 330°–335°, b = ±0 ∘ . 5) for spectral lines in the 7 mm band (42–44 and 48–49 GHz), including CS (1–0), class I CH3OH masers in the 7(0,7)–6(1,6) A+ transition and SiO (1–0) v = 0, 1, 2, 3. MALT-45 is the first unbiased, large-scale, sensitive spectral line survey in this frequency range. In this paper, we present data from the survey as well as a few intriguing results; rigorous analyses of these science cases are reserved for future publications. Across the survey region, we detected 77 class I CH3OH masers, of which 58 are new detections, along with many sites of thermal and maser SiO emission and thermal CS. We found that 35 class I CH3OH masers were associated with the published locations of class II CH3OH, H2O and OH masers but 42 have no known masers within 60 arcsec. We compared the MALT-45 CS with NH3 (1,1) to reveal regions of CS depletion and high opacity, as well as evolved star-forming regions with a high ratio of CS to NH3. All SiO masers are new detections, and appear to be associated with evolved stars from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE). Generally, within SiO regions of multiple vibrational modes, the intensity decreases as v = 1, 2, 3, but there are a few exceptions where v = 2 is stronger than v = 1.

Item Type:	Article
Additional Information:	This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record; Jordan, C. H., Walsh, A. J., Lowe, V., Voronkov, M. A., Ellingsen, S. P., Breen, S. L., Purcell, C. R., Barnes, P. J., Burton, M. G., Cunningham, M. R., Hill, T., Jackson, J. M., Longmore, S. N., Peretto, N., Urquhart, J. S. (2015) MALT-45: a 7 mm survey of the southern Galaxy - I. Techniques and spectral line data, is available online at: http://dx.doi.org/10.1093/mnras/stv178 .
Uncontrolled Keywords:	0201 Astronomical And Space Sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	OXFORD UNIV PRESS
Related URLs:	Author
Date Deposited:	27 May 2015 11:20
Last Modified:	04 Sep 2021 14:19
DOI or ID number:	10.1093/mnras/stv178
URI:	https://researchonline.ljmu.ac.uk/id/eprint/1312

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