On the relative frequencies of core-collapse supernovae sub-types: The role of progenitor metallicity

We show that the observed ratio Nib,c/NII of the subtypes Ib,c and II core-collapse supernovae depends on the metallicity of the host galaxy, as expected on theoretical grounds. However, the observed relation differs considerably from expectations based on nonrotating models of single stars with mass loss. We argue that the predictions of recent models with rotation offer a much better agreement with observations, at least for progenitor stars with solar metallicity; calculations of models with higher and lower metallicities are required in order to substantiate these conclusions. We also suggest that systematic surveys of core collapse supernovae up to redshift Z ~ 1 with the SNAP satellite would allow to probe the effect of metallicity on supernovae properties during the past history of the Universe.