Doctoral Dissertations

Date of Award

8-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

William Hix

Committee Members

Kate Jones, Mike Guidry, Robert, Hinde

Abstract

Using a sophisticated program named CHIMERA, we perform numerical simulations of the end of a massive star's life when its core can no longer support itself through electron degeneracy pressure. After a violent collapse to super-nuclear densities, the core releases its binding energy (10^53 ergs) in the form of neutrinos. Simulations have shown that a small fraction of these neutrinos' energy is deposited into the matter above the forming neutron star, which drives a delayed explosion. Throughout this process, the oxygen and lighter elements that had composed the star's outer-core and envelope experience shock-driven explosive nucleosynthesis, forming newly synthesized heavy elements up to the iron and nickel. At later times in the ejecta, other processes, such as the nu-p-process and possibly the r-process, create elements heavier than iron, which are required to match galactic and solar abundance studies. To follow these nuclear kinetics accurately and to more judiciously model reality, CHIMERA requires an efficient nuclear reaction network of approximately 150 to 300 species. I will discuss my efforts in generalizing CHIMERA's 14-species nuclear reaction network to enable us to more accurately follow the proton-to-nucleon fraction within a complex hydrodynamic flow and the nuclear production and nuclear energy generation rates that results. I will discuss how these improvements have enabled the study of the lower mass limit of core-collapse supernovae. I will discuss the development of our post-processing scheme to extract detailed nucleosynthesis from our state-of-the-art multi-dimensional CHIMERA runs.

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