Type Ia Supernovae Progenitors: Challenges and Opportunities

Lars Bildsten
Kavli Institute for Theoretical Physics

Type Ia supernovae are one of the key tools for cosmological studies of the distant universe. However, our ignorance remains vast as to how they are made, how they explode, and how they may evolve in time. Recent supernovae surveys have revealed a diversity of Type Ia supernovae consistent with our expectation that there are many ways to get a white dwarf to explode. I will review the observational evidence for these distinct populations and I will discuss recent work we have done on a new kind of thermonuclear event from double white dwarfs. These ``.Ia'' supernovae (one-tenth as bright for one-tenth the time as a Type Ia supernovae) should be found in the upcoming surveys at the rate of a few per month, and would directly reveal the population of double white dwarfs in distant galaxies.