TYPE IA SUPERNOVAE - AN EXAMINATION OF POTENTIAL PROGENITORS AND THE REDSHIFT DISTRIBUTION

We examine the possibility that Type Ia supernovae (SNe Ia) are produc ed by white dwarfs accreting from Roche lobe filling evolved companion s, under the assumption that a strong optically thick stellar wind fro m the accretor is able to stabilize the mass transfer. We show that if a mass-transfer phase on a thermal timescale precedes a nuclear-burni ng driven phase, then such systems (of which the supersoft X-ray sourc es are a subgroup) can account for about 10% of the inferred SNe Ia ra te. In addition, we examine the cosmic history of the supernova rate a nd show that the ratio of the rate of SNe Ia to the rate of supernovae produced by massive stars (supernovae of Types II, Ib, Ic) should inc rease from about z = 1 toward lower redshifts.