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MALT-45: a 7 mm survey of the southern Galaxy – I. Techniques and spectral line data

Citation

Jordan, CH and Walsh, AJ and Lowe, V and Voronkov, MA and Ellingsen, SP and Breen, SL and Purcell, CR and Barnes, PJ and Burton, MG and Cunningham, MR and Hill, T and Jackson, JM and Longmore, SN and Peretto, N and Urquhart, JS, 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 (2015) [Refereed Article]


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Copyright 2015 The Authors

DOI: doi:10.1093/mnras/stv178

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 Details

Item Type:Refereed Article
Keywords:masers, surveys, stars:formation, ISM: molecules, galaxy: structure, radio lines: ISM
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Jordan, CH (Mr Christopher Jordan)
Author:Ellingsen, SP (Professor Simon Ellingsen)
ID Code:99349
Year Published:2015
Web of Science® Times Cited:11
Deposited By:Mathematics and Physics
Deposited On:2015-03-20
Last Modified:2017-11-01
Downloads:294 View Download Statistics

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