Relative frequencies of supernovae types: dependence on host galaxy magnitude, galactocentric radius and local metallicity

TL;DR

This study examines how supernovae type ratios depend on host galaxy properties like magnitude, galactocentric radius, and metallicity, revealing key relationships that inform stellar evolution models.

Contribution

It provides a comprehensive analysis of supernova type ratios in relation to galaxy metallicity and position, confirming known dependencies and uncovering new metallicity effects on supernova classifications.

Findings

N(Ibc)/N(II) ratio depends on metallicity, consistent with models.

Recent stellar models with rotation and binaries match observed metallicity dependence.

Unexpected metallicity dependence of thermonuclear to core-collapse supernova ratio.

Abstract

Context: Stellar evolution theory suggests that the relationship between number ratios of supernova (SN) types and metallicity holds important clues as to the nature of the progenitor stars (mass, metallicity, rotation, binarity, etc). Aims: We investigate the metallicity dependence of number ratios of various SN types, using a large sample of SN along with information on their radial position in, and magnitude of, their host galaxy. Methods: We derive typical galaxian metallicities (using the well known metallicity-luminosity relation) and local metallicities, i.e. at the position of the SN; in the latter case, we use the empirical fact that the metallicity gradients in disk galaxies are ~ constant when expressed in dex/R25. Results: We confirm a dependence of the N(Ibc)/N(II) ratio on metallicity; recent single star models with rotation and binary star models with no rotation appear to reproduce equally well that metallicity dependence. The size of our sample does not allow significant conclusions on the N(Ic)/N(Ib) ratio. Finally, we find an unexpected metallicity dependence of the ratio of thermonuclear to core collapse supernovae, which we interpret in terms of the star formation properties of the host galaxies.