Date of Award
Doctor of Philosophy (PhD)
Physics & Astrophysics
Timothy R. Young
This dissertation includes two projects. Part one applies the collapsar model to Bright Linear Type II supernovae. The collapsar model is commonly used to explain gamma-ray bursts. In this model, a stellar core collapses to a black hole surrounded by an accretion disk. In addition to the supernova caused by the core collapse, the black hole powers a high energy jet. Shocks within the jet create the gamma ray burst while the jet's later interaction with circumstellar material creates an afterglow. In a Type II supernova, the hydrogen envelope of the star results in a lower energy jet that does not result in a gamma-ray burst. However, the jet is still mildly relativistic when it interacts with the circumstellar material and generates an afterglow. I present results that some Type II Linear light curves can be modeled as a Type II Plateau plus a jet-related afterglow.
In part two, I examine the morphology of supernova remnants using two different hydrodynamic codes. In particular, I simulate the evolution of a remnant resulting from the explosion of two massive stars and compare the result to that of a single-explosion remnant. Most supernova remnants are assumed to result from the explosion of a single massive star; however, most massive stars are part of systems involving more than one star. Some of these binaries should contain two stars that are each massive enough to end life as a supernova. Results of supernova remnants resulting from different mass stars and circumstellar environments are presented.
In addition, results from two different hydrodynamic codes using the same initial conditions are presented. One of these included the effects of instabilities resulting in 2-dimensional structures. Not including instabilities resulted in the formation of a high density shell. This shell is very Rayleigh-Taylor unstable and breaks up when it expands into an inhomogeneous environment.
Smith, Dean D., "A Collapsar Model For Bright Linear Type II Supernovae And Numerical Simulations Of Multiple, Interacting Supernova Remnants" (2014). Theses and Dissertations. 1713.