Casey Meakin

University of Chicago, FLASH Center

Delayed surface detonation models of thermonuclear supernovae: hydrodynamics and nucleosynthesis

Flame propagation and subsequent detonation in near-Chandrasekhar mass, carbon/oxygen white dwarf stars are studied using multi-dimensional, reactive hydrodynamic simulation. The single point off-center flame ignition models studied by Townsley et al. (2007) are extended through detonation and into the free expansion phase. In these models, detonation occurs in a region at the stellar surface heated by the deflagration ash.

Careful attention is paid to accurately calculating the yield of material burned to nuclear statistical equilibrium (NSE) and then frozen out in the expansion following the detonation wave which sweeps over the white dwarf. A self regulating process comprised of neutronization and pre-expansion leads to ~1.1 Msun of 56Ni synthesized in all of the single point ignition models studied. The yield of intermediate mass elements is ~0.1-0.3 Msun and the explosion energies are all ~1.5*1051 ergs, comparable to observed luminous type Ia supernovae (Ia SNe).

Multi-point ignition can lead to lower luminosity explosions by releasing more energy during the subsonic deflagration phase which goes into expanding the white dwarf prior to detonation. A suite of expanded surface detonation models will be presented which have explosion energies and 56Ni masses spanning those of observed Ia SNe. Synthetic spectra and light curves are being generated from these multi-dimensional models for more direct comparison to observed Ia SNe.

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