We investigate the relationship between the star formation rate (SFR) and dense molecular gas mass in the nuclei of galaxies. To do this, we utilize the observed 850 μm luminosity as a proxy for the infrared luminosity (LIR) and SFR, and we correlate this with the observed CO(J = 3–2) luminosity. We find tentative evidence that the LIR-CO(J = 3–2) index is similar to the Kennicutt-Schmidt (KS) index (N ≈ 1.5) in the central ~1.7 kpc of galaxies, and it flattens to a roughly linear index when including emission from the entire galaxy. This result may imply that the volumetric Schmidt relation is the underlying driver behind the observed SFR-dense gas correlations, and it provides tentative confirmation for recent numerical models. While the data exclude the possibility of a constant LIR-CO(J = 3–2) index for both galaxy nuclei and global measurements at the ~80% confidence level, the considerable error bars cannot preclude alternative interpretations.
“The Star Formation Rate-Dense Gas Relation in the Nuclei of Nearby Galaxies” Narayanan, D., Cox, T.J., Hernquist, L., ApJ, 2008, 681, L77