Multidimensional multiscale dynamics of high-energy astrophysical flows

dc.contributor.advisorWheeler, J. Craigen
dc.contributor.advisorMilosavljević, Milošen
dc.contributor.committeeMemberBromm, Volkeren
dc.contributor.committeeMemberHoeflich, Peteren
dc.contributor.committeeMemberJaffe, Danielen
dc.contributor.committeeMemberKumar, Pawanen
dc.creatorCouch, Sean Michaelen
dc.date.accessioned2010-11-23T20:01:56Zen
dc.date.available2010-11-23T20:01:56Zen
dc.date.available2010-11-23T20:02:09Zen
dc.date.issued2010-05en
dc.date.submittedMay 2010en
dc.date.updated2010-11-23T20:02:09Zen
dc.descriptiontexten
dc.description.abstractAstrophysical flows have an enormous dynamic range of relevant length scales. The physics occurring on the smallest scales often influences the physics of the largest scales, and vice versa. I present a detailed study of the multiscale and multidimensional behavior of three high-energy astrophysical flows: jet-driven supernovae, massive black hole accretion, and current-driven instabilities in gamma-ray burst external shocks. Both theory and observations of core-collapse supernovae indicate these events are not spherically-symmetric; however, the observations are often modeled assuming a spherically-symmetric explosion. I present an in-depth exploration of the effects of aspherical explosions on the observational characteristics of supernovae. This is accomplished in large part by high-resolution, multidimensional numerical simulations of jet-driven supernovae. The existence of supermassive black holes in the centers of most large galaxies is a well-established fact in observational astronomy. How such black holes came to be so massive, however, is not well established. In this work, I discuss the implications of radiative feedback and multidimensional behavior on black hole accretion. I show that the accretion rate is drastically reduced relative to the Eddington rate, making it unlikely that stellar mass black holes could grow to supermassive black holes in less than a Hubble time. Finally, I discuss a mechanism by which magnetic field strength could be enhanced behind a gamma-ray burst external shock. This mechanism relies on a current-driven instability that would cause reorganization of the pre-shock plasma into clumps. Once shocked, these clumps generate vorticity in the post-shock plasma and ultimately enhance the magnetic energy via a relativistic dynamo process.en
dc.description.departmentAstronomyen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-05-1038en
dc.language.isoengen
dc.subjectSupernovaeen
dc.subjectHydrodynamicsen
dc.subjectBlack hole physicsen
dc.subjectAccretionen
dc.subjectCosmic raysen
dc.subjectGamma-ray burstsen
dc.subjectShock wavesen
dc.subjectPlasmasen
dc.subjectInstabilitiesen
dc.titleMultidimensional multiscale dynamics of high-energy astrophysical flowsen
dc.type.genrethesisen
thesis.degree.departmentAstronomyen
thesis.degree.disciplineAstronomyen
thesis.degree.grantorUniversity of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen

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