Molecular Gas in Candidate Double-barred Galaxies. II. Cooler, Less Dense Gas Associated with Stronger Central Concentrations

We have performed a multitransition CO study of the centers of seven double-barred galaxies that exhibit a variety of molecular gas morphologies to determine if the molecular gas properties are correlated with the nuclear morphology and star-forming activity. Near-infrared galaxy surveys have revealed the existence of nuclear stellar bars in a large number of barred or lenticular galaxies. High-resolution CO maps of these galaxies exhibit a …