The Star Formation Rate - Dense Gas Relation in Galaxies as Measured by HCN (3-2) Emission
arXiv:0805.4419 · doi:10.1086/590181
Abstract
We present observations made with the 10m Heinrich Hertz Sub-Millimeter Telescope of HCN (3-2) emission from a sample of 30 nearby galaxies ranging in infrared luminosity from 10^10 - 10^12.5 L_sun and HCN (3-2) luminosity from 10^6 - 10^9 K km s^-1 pc^2. We examine the correlation between the infrared luminosity and HCN (3-2) luminosity and find that the best fit linear regression has a slope (in log-log space) of 0.74+/-0.12. Including recently published data from Gracia-Carpio et al. tightens the constraints on the best-fit slope to 0.79+/-0.09. This slope below unity suggests that the HCN (3-2) molecular line luminosity is not linearly tracing the amount of dense gas. Our results are consistent with predictions from recent theoretical models that find slopes below unity when the line luminosity depends upon the average gas density with a power-law index greater than a Kennicutt-Schmidt index of 1.5.
4 pages, 1 table, 2 figures; accepted to the ApJL
References in corpus (14)
- Some Aspects of Measurement Error in Linear Regression of Astronomical Data
- Diagnostics of irradiated dense gas in galaxy nuclei. II. A grid of XDR and PDR models
- A multi-transition HCN and HCO+ study of 12 nearby active galaxies: AGN versus SB environments
- The Relationship Between Molecular Gas Tracers and Kennicutt-Schmidt Laws
- Evidence of enhanced star formation efficiency in luminous and ultraluminous infrared galaxies
- Is HCN a True Tracer of Dense Molecular Gas in LIRGs and ULIRGs?
- Molecular Star Formation Rate Indicators in Galaxies
- HCN Observations of Dense Star-Forming Gas in High Redshift Galaxies
- HCN versus HCO+ as dense molecular gas mass tracer in Luminous Infrared Galaxies
- Molecular Gas in NUclei of GAlaxies (NUGA): VI. Detection of a molecular gas disk/torus via HCN in the Seyfert2 galaxy NGC6951?
- Observations of Dense Molecular Gas in a Quasar Host Galaxy at z=6.42: Further Evidence for a Non-Linear Dense Gas - Star Formation Relation at Early Cosmic Times
- Rapid Star Formation in the Presence of Active Galactic Nuclei
- The coupling of dynamics and molecular chemistry in galaxies
- The Properties of Dense Molecular Gas in the Milky Way and Galaxies