Date of Award

12-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Physics

Advisor

Leising, Mark

Committee Member

King , Jeremy

Committee Member

Meyer , Bradley

Abstract

Type Ia supernovae (SNe Ia), the thermonuclear explosion of a white dwarf, were once considered standard candles. However, increased observations reveal inhomogeneities in chemical composition and luminosity behavior, roughly dividing SNe Ia into three luminosity classes; super-luminous, sub-luminous, and normally-luminous. After introducing the problem in the context of previous observations and modeling, this thesis explores the physical processes occurring in a SN Ia after explosion, and discusses observations of SN light curves.
A simple model of the expanding ejecta calculates the energy deposition from the decay of radioactive Ni56 as well as photon diffusion. It produces light curves that match early bolometric observations of normal SNe Ia. Variable chemical composition of the ejecta allows for testing a number of explosion scenarios. It becomes apparent that the shape of the light curve is sensitive to the amount and location of synthesized Ni56. Monitoring gamma ray transport through Compton scattering indicates that gamma rays escape at late times. At this epoch an assumption of instantaneous deposition of energy is inaccurate. It is unclear whether positrons escape the ejecta or are trapped at even later times.
The photometry of SN2007ax proved it to be the dimmest and reddest SN Ia observed. SN2008D was serendipitously observed in X-rays before it was even visible in optical light, revealing that an early x-ray outburst may accompany every core collapse SN. Subsequent observations resulted in a well-sampled, multi-band early light curve. Observations of SN2006D, another SN Ia, in B,V,R,I up to about 500 days after maximum light are also presented. The light curve may answer questions about the physics of SNe at late times, if more observations can be included. Future modifications of the simple model and strategies for useful observations are discussed.

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