Building on the archives: Connecting the CN/CO intensity ratio with global galaxy properties in nearby U/LIRGs

Abstract

We use the CN/CO intensity ratio to obtain the dense gas fraction, $f_{\text{dense}}$, for a sample of 16 Ultra-luminous and Luminous Infrared Galaxies and compare $f_{\text{dense}}$ with a suite of global galaxy properties. We find a significant correlation between $f_{\text{dense}}$ and star formation rate calculated using both infrared luminosities and radio continuum, although there is significant scatter in each relation. We find no trend between global or peak $f_{\text{dense}}$ and merger stage. We find no correlation between global $f_{\text{dense}}$ and X-ray luminosity; however, the correlation becomes significant when we measure $f_{\text{dense}}$ at the location of peak X-ray emission. Our interpretation is that the dense gas is co-localized with strong X-ray emission from an active galactic nuclei or strong central star formation.

Accepted to ApJ; 14 pages, 5 figures