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

Context. Stellar evolution theory suggests that the relationship between number ratios of supernova (SN) types and metallicity can provide important information about the physical properties of the progenitor stars (e.g., mass, metallicity, rotation, binarity). Aims. We investigate the metallicity dependence of the number ratios of various SN types, using a large sample of SN along with information about their radial position within, and magnitude of, their host galaxy. Methods. We derive global galaxy gas-phase 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 similar to constant when expressed in dex/R(25). Results. We confirm a dependence of the N(Ibc)/N(II) ratio on metallicity. Single star models with rotation and binary star models with no rotation appear to reproduce equally well the metallicity dependence. The size of our sample does not allow significant conclusions about 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.