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SPLASH: the Southern Parkes Large-Area Survey in Hydroxyl first science from the pilot region


Dawson, JR and Walsh, AJ and Jones, PA and Breen, SL and Cunningham, MR and Lowe, V and Jones, C and Purcell, C and Caswell, JL and Carretti, E and McClure-Griffiths, NM and Ellingsen, SP and Green, JA and Gomez, JF and Krishnan, V and Dickey, JM and Imai, H and Gibson, SJ and Hennebelle, P and Lo, N and Hayakawa, T and Fukui, Y and Mizuno, A, SPLASH: the Southern Parkes Large-Area Survey in Hydroxyl - first science from the pilot region, Monthly Notices of the Royal Astronomical Society, 439, (2) pp. 1596-1614. ISSN 0035-8711 (2014) [Refereed Article]


Copyright Statement

Copyright 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

DOI: doi:10.1093/mnras/stu032


The Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) is a sensitive, unbiased, and fully sampled survey of the southernGalactic plane and Galactic Centre in all four ground-state transitions of the hydroxyl (OH) radical. The survey provides a deep census of 1612-, 1665-, 1667-, and 1720-MHz OH absorption and emission from the Galactic interstellar medium, and is also an unbiased search for maser sources in these transitions. We present here first results from the SPLASH pilot region, which covers Galactic longitudes 334 to 344 and latitudes 2. Diffuse OH is widely detected in all four transitions, with optical depths that are always small (averaged over the Parkes beam), and with departures from local thermodynamic equilibrium common even in the 1665- and 1667-MHz main lines. To a 3σ sensitivity of ∼30 mK, we find no evidence of OH envelopes extending beyond the CO-bright regions of molecular cloud complexes, and conclude that the similarity of the OH excitation temperature and the level of the continuum background is at least partly responsible for this. We detect masers and maser candidates in all four transitions, approximately 50 per cent of which are new detections. This implies that SPLASH will produce a substantial increase in the known population of ground-state OH masers in the southern Galactic plane.

Item Details

Item Type:Refereed Article
Keywords:masers, surveys, molecules, galaxy disc, radiolines, ISM
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Dawson, JR (Dr Joanne Dawson)
UTAS Author:Jones, C (Mrs Courtney Brown)
UTAS Author:Ellingsen, SP (Professor Simon Ellingsen)
UTAS Author:Krishnan, V (Mr Vasaant Krishnan)
UTAS Author:Dickey, JM (Professor John Dickey)
ID Code:90279
Year Published:2014
Funding Support:Australian Research Council (FS100100037)
Web of Science® Times Cited:39
Deposited By:Mathematics and Physics
Deposited On:2014-03-31
Last Modified:2017-11-03
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