CO, HI, recent Spitzer SAGE results in the Large Magellanic Cloud

TL;DR

This study investigates the physical relationship between molecular clouds and atomic hydrogen in the Large Magellanic Cloud, revealing insights into GMC formation and evolution through combined CO and HI data analysis.

Contribution

It presents the first 3D comparison of CO and HI in the LMC, highlighting the growth of GMCs via HI accretion and discussing formation mechanisms involving stellar gravity and supershells.

Findings

Total CO to HI intensity ratio is approximately 0.8 for GMCs.

HI intensity increases with GMC evolutionary stage.

Supports GMC growth via HI accretion over tens of millions of years.

Abstract

Formation of GMCs is one of the most crucial issues in galaxy evolution. I will compare CO and HI in the LMC in 3 dimensional space for the first time aiming at revealing the physical connection between GMCs and associated HI gas at a ~40 pc scale. The present major findings are 1) [total CO intensity] [total HI intensity]0.8 for the 110 GMCs, and 2) the HI intensity tends to increase with the evolution of GMCs. I argue that these findings are consistent with the growth of GMCs via HI accretion over a time scale of a few x 10 Myrs. I will also discuss the role of the background stellar gravity and the dynamical compression by supershells in formation of GMCs.