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Black-Hole Electrodynamics

Citation

Macdonald, Douglas Alan (1984) Black-Hole Electrodynamics. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:09012017-133647841

Abstract

This dissertation considers several aspects of the structure and dynamics of electromagnetic fields around black holes. The four-dimensional, covariant laws of electrodynamics are reformulated in a 3 + 1 (space+time) language in which the key quantities are three-dimensional vectors lying in hypersurfaces of a constant global time t. This formulation is applied to the Blandford-Znajek model of power generation in quasars, which consists of a supermassive black hole surrounded by an accretion disk that holds a magnetic field on the hole, with the rotational energy and angular momentum of the hole and disk being extracted by electromagnetic torques. The 3 + 1 formalism allows the theory of stationary, axisymmetric black holes and their magnetospheres to be couched in an "absolute-space/universal-time" language very similar to the flat­ spacetime theory of pulsar electrodynamics; and this similarity allows fiat-space pulsar concepts to be extended to curved-space black holes. The Blandford­-Znajek quasar model is reformulated in terms of a DC circuit-theory analysis, and action principles describing the overall structure of the magnetosphere and the field distribution on the horizon are developed. A general prescription for constructing global models of force-free magnetospheres is developed and this prescription is used to generate numerical models of black-hole magneto­spheres for a variety of field configurations and black-hole angular velocities. The electromagnetic boundary conditions at the horizon of a black hole are described in terms of a recently developed "membrane viewpoint". The necess­ity and efficacy of using a "stretched horizon" in the membrane viewpoint is discussed, and is illustrated by two simple dynamical problems involving electromagnetic fields near black-hole horizons.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Thorne, Kip S.
Group:TAPIR
Thesis Committee:
  • Blandford, Roger D. (chair)
  • Cowan, Eugene W.
  • Wise, Mark B.
  • Thorne, Kip S.
Defense Date:7 November 1983
Funders:
Funding AgencyGrant Number
NSFAST79-22012
NSFAST82-14126
NSFPHY77-27084
Record Number:CaltechTHESIS:09012017-133647841
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:09012017-133647841
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/198.2.339DOIArticle adapted for Chapter II.
https://doi.org/10.1093/mnras/198.2.345DOIArticle adapted for Chapter III.
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10410
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:06 Sep 2017 20:23
Last Modified:19 Sep 2018 16:52

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