Dwarf merging makes for an explosive combo

Type Ia supernovae are very important exploding stars. Astronomers have always assumed that the accretion scenario is the far more common of the two, because it takes a long time for two dwarfs to merge, whereas accretion can happen easily if a dwarf happens to be paired up with a normal star. In other words, their observations strongly favor the idea that it’s the merger of white dwarfs that cause Type Ia supernovae. I asked this question specifically at the Chandra press conference, and was told that the two different scenarios produce explosions with pretty much the same energy, so this may only affect cosmological measurements a small amount. I remember reading a long technical paper about the different Type Ia scenarios back then: it’s been a mystery for a long, long time.