Comparing the Locations of Supernovae to CO (2-1) Emission in their Host Galaxies

Abstract

We measure the molecular gas environment near recent ($<100$ yr old) supernovae (SNe) using $\sim 1^{\prime \prime }$ or $\le 150$pc resolution CO (2-1) maps from the PHANGS-ALMA survey of nearby star-forming galaxies. This is arguably the first such study to approach the scales of individual massive molecular clouds ($M_{\mathrm{mol}}\gtrsim 10^{5.3}$ M${}_{\odot }$). Using the Open Supernova Catalog (OSC), we identify 63 SNe within the PHANGS-ALMA footprint. We detect CO (2-1) emission near $\sim 60\%$ of the sample at 150pc resolution, compared to $\sim 35\%$ of map pixels with CO (2-1) emission, and up to $\sim 95\%$ of the SNe at 1kpc resolution compared to $\sim 80\%$ of map pixels with CO (2-1) emission. We expect the $\sim 60\%$ of SNe within the same 150pc beam as a GMC will likely interact with these clouds in the future, consistent with the observation of widespread SN-molecular gas interaction in the Milky Way, while the other $\sim 40\%$ of SNe without strong CO (2-1) detections will deposit their energy in the diffuse interstellar medium (ISM), perhaps helping drive large-scale turbulence or galactic outflows. Broken down by type, we detect CO (2-1) emission at the sites of $\sim 85\%$ of our 9 stripped-envelope SNe (SESNe), $\sim 40\%$ of our 34 Type II SNe, and $\sim 35\%$ of our 13 Type Ia SNe, indicating that SESNe are most closely associated with the brightest CO (2-1) emitting regions in our sample. Our results confirm that SN explosions are not restricted to only the densest gas, and instead exert feedback across a wide range of molecular gas densities.

Accepted to ApJ; 38 pages, 12 figures, 7 tables in two-column AASTEX63 format