Testing the Larson relations in massive clumps

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 α_vir on mass (and radius) is only a function of the gravitational energy, independent of the kinetic energy of the system; thus, α_vir 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

http://hdl.handle.net/20.500.12386/30830

Url

https://academic.oup.com/mnras/article/477/2/2220/4990719

Issn Identifier

0035-8711

Ads BibCode

2018MNRAS.477.2220T

Rights

open.access

File(s)

Name

Traficante_2018b.pdf

Description

PDF editoriale

Size

1.53 MB

Format

Adobe PDF

Checksum (MD5)

74ae7386b3be3f843f354bd1e50c988e

Testing the Larson relations in massive clumps

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