Dense gas in local galaxies revealed by multiple tracers

Abstract

We present 3 mm and 2 mm band simultaneously spectroscopic observations of HCN 1-0, HCO${}^{+}$ 1-0, HNC 1-0, and CS 3-2 with the IRAM 30 meter telescope, toward a sample of 70 sources as nearby galaxies with infrared luminosities ranging from several 10${}^5{L}_{\odot }$ to more than 10${}^{12}{L}_{\odot }$. After combining HCN 1-0, HCO${}^{+}$ 1-0 and HNC 1-0 data from literature with our detections, relations between luminosities of dense gas tracers (HCN 1-0, HCO${}^{+}$ 1-0 and HNC 1-0) and infrared luminosities are derived, with tight linear correlations for all tracers. Luminosities of CS 3-2 with only our observations also show tight linear correlation with infrared luminosities. No systematic difference is found for tracing dense molecular gas among these tracers. Star formation efficiencies for dense gas with different tracers also do not show any trend along different infrared luminosities. Our study also shows that HCN/HCO${}^{+}$ line ratio might not be a good indicator to diagnose obscured AGN in galaxies.

25 pages, 5 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (10)

• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• A multi-transition HCN and HCO+ study of 12 nearby active galaxies: AGN versus SB environments
• Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
• 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?
• HCN Observations of Dense Star-Forming Gas in High Redshift Galaxies
• Millimeter Interferometric HCN(1-0) and HCO+(1-0) Observations of Luminous Infrared Galaxies
• A Hard X-ray Test of HCN Enhancements as a Tracer of Embedded Black Hole Growth
• The Star Formation Rate - Dense Gas Relation in Galaxies as Measured by HCN (3-2) Emission
• CARMA Survey toward Infrared-bright Nearby Galaxies (STING). IV. Spatially Resolved 13CO in Spiral Galaxies

Cited by in corpus (6)

• Tracing Interstellar Heating: An ALCHEMI Measurement of the HCN Isomers in NGC 253
• A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde IV. The ALMA view of N113 and N159W in the LMC
• Opacities of dense gas tracers in galactic massive star-forming regions
• CN 2-1 and CS 5-4 observations toward Arp 299 with the SMA
• Physical Conditions in the LMC's Quiescent Molecular Ridge: Fitting Non-LTE Models to CO Emission