Multidimensional multiscale dynamics of high-energy astrophysical flows


Multidimensional multiscale dynamics of high-energy astrophysical flows

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dc.contributor.advisor Wheeler, J. Craig
dc.contributor.advisor Milosavljević, Miloš
dc.creator Couch, Sean Michael 2010-11-23T20:01:56Z 2010-11-23T20:02:09Z 2010-11-23T20:01:56Z 2010-11-23T20:02:09Z 2010-05 2010-11-23 May 2010
dc.description.abstract Astrophysical 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.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subject Supernovae
dc.subject Hydrodynamics
dc.subject Black hole physics
dc.subject Accretion
dc.subject Cosmic rays
dc.subject Gamma-ray bursts
dc.subject Shock waves
dc.subject Plasmas
dc.subject Instabilities
dc.title Multidimensional multiscale dynamics of high-energy astrophysical flows 2010-11-23T20:02:09Z
dc.contributor.committeeMember Bromm, Volker
dc.contributor.committeeMember Hoeflich, Peter
dc.contributor.committeeMember Jaffe, Daniel
dc.contributor.committeeMember Kumar, Pawan
dc.description.department Astronomy
dc.type.genre thesis
dc.type.material text Astronomy Astronomy University of Texas at Austin Doctoral Doctor of Philosophy

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