Constraints on the massive supernova progenitors

The generally-accepted scheme distinguishes two main classes of supernovae (SNe): Ia resulting from the old stellar population (deflagration of a white dwarf in close binary systems), and SNe of type II and Ib/c whose ancestors are young massive stars (died in a core-collapse explosion). Concerning the latter, there are suggestions that the SNe II are connected to early B stars, and SNe Ib/c to isolated O or Wolf-Rayet (W-R) stars. However, little or no effort was made to further separate SNe Ib from Ic. We have used assumed SN rates for different SN types in spiral galaxies in an attempt to perform this task. If the isolated progenitor hypothesis is correct, our analysis indicates that SNe Ib result from stars of main-sequence mass 23M(circle dot) less than or similar to M less than or similar to 30M(circle dot), while the progenitors of SNe Ic are more massive stars with M greater than or similar to 30M(circle dot). Alternatively, if the majority of SNe Ib/c appear in close binary systems (CBs) then they would result from the same progenitor population as most of the SNe II, i.e. early B stars with initial masses of order M similar to 10M(circle dot). Future observations of SNe at high-redshift (z) and their rate will provide us with unique information on SN progenitors and the star-formation history of galaxies. At higher-z (deeper in the cosmic past), we expect to see the lack of type Ia events, i.e. the dominance of core-collapse SNe. Better understanding of the stripped-envelope SNe (Ib/c), and their potential use as distance indicators at high-z, would therefore be of great practical importance.