The Star Formation Rate - Dense Gas Relation in the Nuclei of Nearby Galaxies

Abstract

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 micron luminosity as a proxy for the infrared luminosity and SFR, and 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 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 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.

arXiv commentAccepted at ApJ Letters

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• The Big Problems in Star Formation: the Star Formation Rate, Stellar Clustering, and the Initial Mass Function
• Submillimetre galaxies in a hierarchical universe: number counts, redshift distribution, and implications for the IMF
• The CO-H2 Conversion Factor in Disc Galaxies and Mergers
• The kiloparsec-scale star formation law at redshift 4: wide-spread, highly efficient star formation in the dust-obscured starburst galaxy GN20
• A Theory for the Excitation of CO in Star Forming Galaxies
• Survival of Star-Forming Giant Clumps in High-Redshift Galaxies
• Resolving The Generation of Starburst Winds in Galaxy Mergers
• Dense Molecular Gas: A Sensitive Probe of Stellar Feedback Models
• The Cosmic Evolution of the IMF Under the Jeans Conjecture with Implications for Bottom-Heavy Ellipticals
• The Kennicutt-Schmidt Star Formation Relation at z~2
• Hyper-Eddington Black Hole Growth in Star-Forming Molecular Clouds and Galactic Nuclei: Can It Happen?
• Dense-gas tracers and carbon isotopes in five 2.5<z<4 lensed dusty star forming galaxies from the SPT SMG sample