A CO Survey of the LMC with NANTEN: II. Catalog of Molecular Clouds

Abstract

Abstract From a 12CO ($J=1 \hbox{--} 0$) survey with the NANTEN telescope, we present a complete catalog of giant molecular clouds (GMCs) in the Large Magellanic Cloud. In total, 107 CO clouds have been identified, 55 of which were detected at more than 3 observed positions. For the 55 clouds, the physical properties, such as size, line-width, virial mass, and CO luminosity, are cataloged. From a statistical analysis of these quantities, we show that GMCs in the LMC are close to gravitational equilibrium. A comparison with H i data indicates that most of the CO clouds are distributed in dense parts of H i gas, whose H i column density is greater than $10^{21} \,\mathrm{cm}^{-2}$. It is notable that the mass ratio of the molecular-to-atomic hydrogen of the lower radial velocity component of gas is $\sim 0.2$, which is a factor of 2 higher than that of the gaseous-disk component, $\sim 0.1$. Molecular clouds are apparently formed efficiently in the parent atomic clouds in the lower velocity component. The CO Arc, which is a few kpc scale ordered structure of CO clouds along the southern optical edge of the galaxy, corresponds well to the the lower velocity component of H i gas.