EAPSI: Detailed Three-Dimension Simulations of an Unexplored Progenitor System for Type Ia Supernovae

Jenks Malia, Norman OK

Investigators

Abstract

Type Ia supernovae are thermonuclear explosions of white dwarf stars. They are great cosmic probes because their brightness is almost always the same and can be standardized empirically. These objects were used to discover the Dark Energy in 1999, an accomplishment recognized with the Nobel Prize in 2011. However, the nature of the stars that blow up?the progenitor system?remains a bit of a mystery. The mass of the white dwarf is increased by accreting material from its companion star. While Type Ia supernovae have been studied for over 30 years the progenitor system for these explosions is still disputed. This project seeks to study one proposed progenitor system that has remained largely unexplored. In collaboration with Keiichi Maeda, an expert in dynamical explosion models, at Kyoto University the researcher will create a computer simulation of a Type Ia supernova from the merger of two white dwarfs of differing masses. This simulation will explore the case where the less massive white dwarf is tidally disrupted and accretes onto the more massive white dwarf. This model is expected to resolve some discrepancies between previous models and observations. A better understanding of the progenitor system will improve its usefulness to as probes of the nature of Universe. This project will create a hydrodynamic simulation of a Type Ia supernova from a tidally disrupted double degnerate merger. This simulation will be used to test several properties of this type of explosion. It will explore the range of possible explosion masses due to spin up. This would allow this model to fit both Chandrasekhar mass as well as superchandra explosions. This explosion type should not be easily observable as a supersoft X-ray source, and should be a nearly spherical explosion. Both of these will make it compatible with current observational constraints. This model can test the abundances predicted from this type of explosion and test for the presence of carbon at low explosion velocities. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.