A Catalog of HI Clouds in the Large Magellanic Cloud

TL;DR

This study catalogs HI clouds in the Large Magellanic Cloud, revealing their size, velocity, and mass distributions, and analyzing their dynamical states and turbulence characteristics.

Contribution

It provides a comprehensive catalog of HI clouds in the LMC with detailed analysis of their physical properties and distributions, using combined interferometric and single-dish data.

Findings

HI clouds follow Larson Law scaling with steeper indices in hot regions.

Cloud virial parameters suggest turbulence dominates gravity.

Mass distribution follows a power law, surface density is log-normal.

Abstract

A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud (LMC) combined with the Parkes multi-beam HI single-dish survey clearly shows that the HI gas is distributed in the form of clumps or clouds. The HI clouds and clumps have been identified using a thresholding method with three separate brightness temperature thresholds ($T_b$). Each catalog of HI cloud candidates shows a power law relationship between the sizes and the velocity dispersions of the clouds roughly following the Larson Law scaling $\sigma_v \propto R^{0.5}$, with steeper indices associated with dynamically hot regions. The clouds in each catalog have roughly constant virial parameters as a function mass suggesting that that the clouds are all in roughly the same dynamical state, but the values of the virial parameter are significantly larger than unity showing that turbulent motions dominate gravity in these clouds. The mass distribution of the clouds is a power law with differential indices between -1.6 and -2.0 for the three catalogs. In contrast, the distribution of mean surface densities is a log-normal distribution.