Physical Conditions in the LMC's Quiescent Molecular Ridge: Fitting Non-LTE Models to CO Emission; Data Cubes

Data cubes to accompany "Physical Conditions in the LMC's Quiescent Molecular Ridge: Fitting Non-LTE Models to CO Emission". 

Abstract: The Molecular Ridge in the LMC extends several kiloparsecs south from 30 Doradus, and it contains ~30% of the molecular gas in the entire galaxy. However, the southern end of the Molecular Ridge is quiescent---it contains almost no massive star formation, which is a dramatic decrease from the very active massive star forming regions 30 Doradus, N159, and N160.
We present new ALMA and APEX observations of the Molecular Ridge at a resolution as high as ~16'' (~3.9 pc) with molecular lines 12CO(1-0), 13CO(1-0), 12CO(2-1), and 13CO(2-1). We analyze these emission lines with our new multi-line non-LTE fitting tool to produce maps of kinetic temperature, H2 volume density, and CO column density across the region based on models from RADEX. Using simulated data for a range of parameter space for each of these variables, we evaluate how well our fitting method can recover these physical parameters for the given set of molecular lines. We then compare the results of this fitting with LTE and X_CO methods of obtaining mass estimates and how line ratios correspond with physical conditions. We find that this fitting tool allows us to more directly probe the physical conditions of the gas and estimate values of temperature, density, and column density that are less subject to the effects of optical depth and line-of-sight projection than previous methods. The fitted H2 density values show a strong correlation with the presence of, and both total and average mass of associated YSOs, while typical star formation diagnostics such as mean density, surface density, dense gas fraction, and virial parameter do not show as strong a correlation.