The Dynamical State of Massive Clumps

Abstract

The dynamical state of massive clumps is key to our understanding of the formation of massive stars. In this work, we study the kinematic properties of massive clumps using synthetic observations. We have previously compiled a very large catalog of synthetic dust-continuum compact sources from our 250 pc, SN-driven, star formation simulation. Here, we compute synthetic ${\mathrm{N}}_2{\mathrm{H}}^{+}$ line profiles for a subsample of those sources and compare their properties with the observations and with those of the corresponding three-dimensional (3D) clumps in the simulation. We find that the velocity dispersion of the sources estimated from the ${\mathrm{N}}_2{\mathrm{H}}^{+}$ line is a good estimate of that of the 3D clumps, although its correlation with the source size is weaker than the velocity-size correlation of the 3D clumps. The relation between the mass of the 3D clumps, $M_{\mathrm{main}}$, and that of the corresponding synthetic sources, $M_{\mathrm{SED}}$, has a large scatter and a slope of 0.5, $M_{\mathrm{main}}\propto M_{\mathrm{SED}}^{0.5}$, due to uncertainties arising from the observational band-merging procedure and from projection effects along the line of sight. As a result, the virial parameters of the 3D clumps are not correlated with the clump masses, even if a negative correlation is found for the compact sources, and the virial parameter of the most massive sources may significantly underestimate that of the associated clumps.

19 pages, 12 figures, 1 table. Accepted for publication in MNRAS

References in corpus (13)

• Structural Analysis of Molecular Clouds: Dendrograms
• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• A High Order Godunov Scheme with Constrained Transport and Adaptive Mesh Refinement for Astrophysical MHD
• Properties of Hi-GAL clumps in the inner Galaxy]{The Hi-GAL compact source catalogue. I. The physical properties of the clumps in the inner Galaxy ($-71.0^{\circ }<\ell <67.0^{\circ }$)
• Infall-Driven Protostellar Accretion and the Solution to the Luminosity Problem
• The Green Bank Ammonia Survey: Dense Cores Under Pressure in Orion A
• Massive and low-mass protostars in massive "starless" cores
• Characterizing the properties of cluster precursors in the MALT90 survey
• Massive 70 micron quiet clumps I: evidence of embedded low/intermediate-mass star formation activity
• SOC program for dust continuum radiative transfer
• LOC program for line radiative transfer
• Are massive dense clumps truly sub-virial? A new analysis using Gould Belt ammonia data
• Physical Properties and Real Nature of Massive Clumps in the Galaxy