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Probing type Ia supernovae through simulations and observations: a thesis in Physics
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Probing type Ia supernovae through simulations and observations: a thesis in Physics

Vishal Tiwari
Master of Science (MS), University of Massachusetts Dartmouth
2020
DOI:
https://doi.org/10.62791/20082

Abstract

Type Ia supernovae (SNe Ia) are the thermonuclear explosions of carbon-oxygen white dwarfs in binary systems with another white dwarf, or a main sequence or red giant star. The nature of the stellar companion star, and the mechanism by which the white dwarf explodes are some of the long-lasting mysteries in astrophysics. To probe their nature, we are exploring the dynamically-driven double-degenerate double detonation model. In this proposed model, a carbon-oxygen (CO) white dwarf in a binary system with another CO white dwarf with thin surface helium shells can lead to a surface helium detonation. This surface detonation in turn can lead to the detonation of the carbon in the core. I explore three-dimensional hydrodynamical simulations of the D6 model using the Eulerian grid code FLASH. Additionally, I have turned to the observations of the late-time light curves of SNe Ia to put constraints on the nature of the progenitors. From the late-time (> 300 days) observations of SNe Ia light curves, the rate of decay of the light-curve slows. An extra source of energy is thought to arise from the radioactive decay of the neutron-rich isotope 57Ni, which is a long-lived neutron-rich radioisotope that can be used to distinguish between a Chandrasekhar mass (MCh) white dwarf and a sub-Chandrasekhar mass (sub-MCh) white dwarf progenitor. In this work, we have compared nucleosynthetic yields of 57Ni from simulations spanning a wide range of parameter space of MCh and sub-MCh models and compared these against the yields inferred from five SNe Ia.
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