A Catalog of H I Clouds in the Large Magellanic Cloud

Abstract

A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud (LMC) combined with the Parkes multibeam H I single-dish survey clearly shows that the H I gas is distributed in the form of clumps or clouds. The H I clouds and clumps have been identified using a thresholding method with three separate brightness temperature thresholds (Tb). Each catalog of H I cloud candidates shows a power-law relationship between the sizes and the velocity dispersions of the clouds roughly following the Larson law scaling σv ∝ R0.5, with steeper indices associated with dynamically hot regions. The clouds in each catalog have roughly constant virial parameters as a function of mass, suggesting 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 lognormal distribution. Show more