The Progenitors of Type Ia Supernovae

Abstract

Models for Type Ia Supernovae (SNe Ia) are reviewed. It is shown that there are strong reasons to believe that SNe Ia represent thermonuclear disruptions of C-O white dwarfs, when these white dwarfs reach the Chandrasekhar limit and ignite carbon at their centers. Progenitor scenarios are reviewed critically and the strengths and weaknesses of each scenario are explicitly presented. It is argued that single-degenerate models, in which the white dwarf accretes from a subgiant or giant companion are currently favored. The relation of the different models to the use of SNe Ia for the determination of cosmological parameters is also discussed. Observational tests of the conclusions are suggested.