Donald E. Willcox
PhD candidate in the Department of Physics & Astronomy
'White Dwarfs as Type Ia Supernovae Progenitors'
Synopsis: Advances in computational capability have enabled exploration of a variety of progenitor systems for Type Ia Supernovae (SNIa), brilliant stellar explosions powered by the thermonuclear burning of carbon and oxygen from a white dwarf. The nucleosynthesis during these events yields nickel-56, the decay of which sustains the large optical luminosity of a SNIa explosion. SNIa are sufficiently brilliant and standardizable to permit their use as cosmological distance indicators, with important implications for characterizing the effects of dark energy on the expansion of the universe. Nevertheless, an important open problem remains in that the nature of the SNIa progenitor system is unknown. It is theoretically possible for a SNIa to ensue from the thermonuclear runaway of a single Chandrasekhar-mass white dwarf, from the double detonation of a sub-Chandrasekhar mass white dwarf, or from the collision or merger of two white dwarfs. It is thus the task of the SNIa modeling community to determine the feasibility of these proposed progenitor systems as well as their observational characteristics for comparison to actual SNIa. The ultimate goal of these efforts is to understand physically the observed variance in SNIa, thereby increasing the precision with which SNIa can be used for cosmological studies. This talk will review our present understanding of proposed SNIa progenitor systems from observations as well as recent modeling efforts using multidimensional hydrodynamics. For each system, simulation results will be highlighted along with the ongoing challenges faced in using modeling to understand the observational characteristics of SNIa. The talk will also provide an overview of future developments that will be needed to determine which of the proposed white dwarf progenitor systems are responsible for the observed SNIa and in what proportions.
Biography: Donald E. Willcox is a PhD candidate in Stony Brook's Department of Physics & Astronomy. He focuses on the systematics of ignition leading to Type Ia Supernovae, the thermonuclear incineration of white dwarf stars, and is particularly interested in the role of coupled electron capture and beta decay processes in setting the properties of convection. Donald obtained bachelor's degrees in Electrical Engineering and Engineering Physics from LeTourneau University in 2011 in his home state of Texas. He is a Turner Fellow in the Center for Inclusive Education.
Wednesday, June 28, 2017 at 12:30 PM