Comparisons of the radial distributions of core-collapse supernovae with those of young and old stellar populations☆

We present observational constraints on the nature of core-collapse (CC) supernovae (SNe) through an investigation into their radial distributions with respect to those of young and old stellar populations within their host galaxies, as traced by H alpha emission and R-band light, respectively. We discuss results and the implications they have on the nature of SN progenitors, for a sample of 177 CC SNe. We find that the radial positions of the overall CC population closely follow the radial distribution of H alpha emission, implying that both are excellent tracers of star formation within galaxies. Within this overall distribution, we find that there is a central deficit of SNII which is offset by a central excess of SNIb/c. This implies a strong metallicity dependence on the relative production of the two types, with SNIb/c arising from higher metallicity progenitors than SNII. Separating the SNIb/c into individual classes, we find that a trend emerges in terms of progenitor metallicity going from SNII through SNIb to SNIc, with the latter arising from the highest metallicity progenitors.