Narrow absorption lines from intervening material in supernovae

The interstellar medium (ISM) has a number of tracers such as the NaI Dλλ 5890, 5896 absorption lines that are evident in the spectra of galaxies but also in those of individual astrophysical sources such as stars, novae, or quasars. Here, we investigate narrow absorption features in the spectra of nearby supernovae (SNe) and compare them to local (<0.5 kpc) and global host galaxy properties. With a large and heterogeneous sample of spectra, we are able to recover the known relations of ISM with galaxy properties: larger columns of ISM gas are found in environments that are more massive, more actively star-forming, younger, and viewed from a more inclined angle. Most trends are stronger for local properties than global properties, and we find that the ISM column density decreases exponentially with the offset from the host galaxy centre, as expected for a gas distribution following an exponential radial profile. We also confirm trends for the velocity of galactic outflows increasing with radius. The current study demonstrates the capability of individual light sources to serve as ubiquitous tracers of ISM properties across various environments and galaxies.