Type Ia supernovae

Abstract

Type Ia supernovae are the biggest thermonuclear explosions in the modern universe and responsible for making about 2/3 of the iron in our blood. They also play a special role as calibratable standard candles in cosmology, yet our understanding of them is primitive. We discuss reecent attempts in theory and simulation to describe more physically the ignition of the runaway in a carbon-oxygen white dwarf; the possible transition of burning to detonation; and the light curves, nucleosynthesis, and spectra of multi-dimensional models. The convection prior to ignition sets up a dipole-flow that implies off-center, lopsided ignition with an offset that depends on the rotation of the white dwarf. Once the flame ignites, an extended period of subsonic burning is followed by a transition to a detonation that happens when the burning enters the "stirred flame" regime. In terms of combustion parameters, the required conditions for detonation are Karlovitz numbers much greater than 10 and Damköhler numbers of approximately 10. Multi-dimensional models employing these ignition and detonation criteria give good agreement with the observed light curves and spectra of supernovae and with the observed width-luminosity relation. The data base generated by these models will be useful in planning future SN Ia survey missions. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlikeLicence.