Supersoft X‐ray sources and the progenitors of Type Ia supernovae

Supersoft X‐ray sources have been proposed as one of the major channels to produce Type Ia supernovae (SNe Ia). However, the true nature of the progenitors has remained an unsolved problem. In this review I summarize the present status of our understanding of SN Ia progenitors, the main classes of progenitor models and recent observational constraints. At present, neither the single‐degenerate nor the double‐degenerate model can be ruled out, and indeed more than one channel may be required to explain the observed SN Ia diversity. Finally, I discuss the origin of the lightcurve peak – lightcurve width relation (the ‘Phillips relation’) and show that it is expected to depend on metallicity; this needs to be taken into account in high‐precision cosmological applications (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)