Local Environments of Low-redshift Supernovae

We characterize the local (2 kpc sized) environments of Type Ia, II, and Ib/c supernovae (SNe) that have recently occurred in nearby (d less than or similar to 50 Mpc) galaxies. Using ultraviolet (UV; from Galaxy Evolution Explorer) and infrared (IR; from Wide-field Infrared Survey Explorer) maps of 359 galaxies and a sample of 472 SNe, we measure the star formation rate surface density (sigma(SFR)) and stellar mass surface density (sigma) in a 2 kpc beam centered on each SN site. We show that core-collapse SNe are preferentially located along the resolved galactic star-forming main sequence, whereas Type Ia SNe are extended to lower values of sigma(SFR) at fixed sigma, indicative of locations inside quiescent galaxies or quiescent regions of galaxies. We also test how well the radial distribution of each SN type matches the radial distributions of UV and IR light in each host galaxy. We find that, to first order, the distributions of all types of SNe mirror those of both near-IR light (3.4 and 4.5 mu m, tracing the stellar mass distribution) and mid-IR light (12 and 22 mu m, tracing emission from hot, small grains), and also resemble our best-estimate sigma(SFR). All types of SNe appear more radially concentrated than the UV emission of their host galaxies. In more detail, the distributions of Type II SNe show small statistical differences from those of near-IR light. We attribute this overall structural uniformity to the fact that within any individual galaxy, sigma(SFR) and sigma track one another well, with variations in sigma(SFR)/sigma most visible when comparing between galaxies.

Automated summary

The study reveals that core-collapse supernovae tend to lie along the resolved galactic star-forming main sequence, while Type Ia supernovae are more likely to be found in quiescent galaxies or regions. All types of supernovae are more radially concentrated than the UV emission of their host galaxies, with Type II supernovae showing small statistical differences from the near-IR light distribution. This overall structural uniformity is attributed to the tracking relationship between star formation rate surface density and stellar mass surface density within individual galaxies.