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Molecular Line Emission Towards High-Mass Clumps: The MALT90 Catalogue

Rathborne, JM and Whitaker, JS and Jackson, JM and Foster, JB and Contreras, Y and Stephens, IW and Guzman, AE and Longmore, SN and Sanhueza, P and Schuller, F and Wyrowski, F and Urquhart, JS (2016) Molecular Line Emission Towards High-Mass Clumps: The MALT90 Catalogue. PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA, 33. ISSN 1323-3580

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Abstract

The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass clumps. Recently completed, it mapped 90 GHz line emission toward 3246 high-mass clumps identified from the ATLASGAL 870 �m Galactic plane survey. By utilising the broad frequency coverage of the Mopra telescope's spectrometer, maps in 16 different emission lines were simultaneously obtained. Here we describe the �first line catalog of the detected emission, generated by Gaussian profile �fitting to spectra extracted toward each clumps' dust peak. Synthetic spectra show that the catalog has a completeness of >95%, a probability of a false-positive detection of <0.3%, and a relative uncertainty in the measured quantities of <20% over the range of detection criteria. We find that the detection rates are highest for the (1{0) molecular transitions of HCO+, HNC, N2H+, and HCN (72{88%). The majority of clumps (~� 95%) are detected in at least one of the molecular transitions, just under half of the clumps (�~48%) are detected in 4 or more of the transitions, while only 2 clumps are detected in 13 or more transitions. We find several striking trends in the ensemble of properties for the different molecular transitions when plotted as a function of the clumps' evolutionary state. In particular, the optically thickest HCO+ emission shows a `blue-red asymmetry' that indicates overall collapse that monotonically decreases as the clumps evolve. This catalog represents the largest compiled database of molecular line emission toward high-mass clumps and is a valuable data set for detailed studies of these objects.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: CAMBRIDGE UNIV PRESS
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Date Deposited: 12 Sep 2016 13:30
Last Modified: 07 Sep 2017 13:19
DOI or Identification number: 10.1017/pasa.2016.23
URI: http://researchonline.ljmu.ac.uk/id/eprint/4139

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