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Full-Text Articles in Physical Sciences and Mathematics
Non-Axisymmetric Instabilities In Self-Gravitating Tori Around Black Holes, And Solving Einstein Constraints With Superconvergent Finite Element Methods, Oleg Korobkin
LSU Doctoral Dissertations
This thesis contains results on two related projects. In the first project, we explore non-axisymmetric instabilities in general relativistic accretion disks around black holes. Such disks are created as transient structures in several astrophysical scenarios, including mergers of compact objects and core collapse of massive stars. These disks are suggested for the role of cenral engines of gamma-ray bursts. We address the stability of these objects against the runaway and non-axisymmetric instabilities in the three-dimensional hydrodynamical fully general relativistic treatment. We explore three slender and moderately slender disk models with varying disk-to-black hole mass ratio. None of the models that …
Studies Of States And State Transitions In Low Mass X-Ray Binaries, Charles Bradley
Studies Of States And State Transitions In Low Mass X-Ray Binaries, Charles Bradley
LSU Doctoral Dissertations
We investigate the model of a disk/coronal accretion flow into a black hole. We build a numerical code to ascertain whether the inner regions of an accretion disk in X-ray binaries can transform from a cool standard disk to an advection-dominated flow through the known properties of Coulomb interaction in a two-temperature plasma, taking into account viscous heating, standard radiation processes, and thermal conduction. A hot, diffuse corona covering the whole disk is powered by accretion, but it exchanges energy with the underlying cool disk through radiative interactions and conduction. If the accretion rate is low enough, at some intermediate …
Mass Transfer And Evolution Of Compact Binary Stars, Vayujeet Gokhale
Mass Transfer And Evolution Of Compact Binary Stars, Vayujeet Gokhale
LSU Doctoral Dissertations
We present a study of key aspects of the evolution of binary stars with emphasis on binaries consisting of two white dwarf stars. The evolution of such systems is driven by the loss of angular momentum by gravitational wave radiation. Effects like mass transfer and other modes of angular momentum loss and redistribution influence the evolutionary fate of the binary, and can lead to a merger, the tidal disruption of one of the components or its survival as a long-lived AM Canum Venaticorum (AM CVn) type system. Our study takes into account some of these effects; like mass loss, tides, …