Testing the Larson relations in massive clumps

Journal
Date Issued
2018
Author(s)
•
Duarte-Cabral, A.
•
•
Fuller, G. A.
•
Merello, M.
•
•
Peretto, N.
•
•
DOI
Abstract
We tested the validity of the three Larson relations in a sample of 213 massive clumps selected from the Herschel infrared Galactic Plane (Hi-GAL) survey, also using data from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey of 3-mm emission lines. The clumps are divided into five evolutionary stages so that we can also discuss the Larson relations as a function of evolution. We show that this ensemble does not follow the three Larson relations, regardless of the clump's evolutionary phase. A consequence of this breakdown is that the dependence of the virial parameter αvir on mass (and radius) is only a function of the gravitational energy, independent of the kinetic energy of the system; thus, αvir is not a good descriptor of clump dynamics. Our results suggest that clumps with clear signatures of infall motions are statistically indistinguishable from clumps with no such signatures. The observed non-thermal motions are not necessarily ascribed to turbulence acting to sustain the gravity, but they might be a result of the gravitational collapse at the clump scales. This seems to be particularly true for the most massive (M ≥ 1000 M☉) clumps in the sample, where exceptionally high magnetic fields might not be enough to stabilize the collapse.
Volume
477
Issue
2
Start page
2220
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2018MNRAS.477.2220T
Rights
open.access
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