A Caltech Library Service

Black-Hole Electrodynamics


Macdonald, Douglas Alan (1984) Black-Hole Electrodynamics. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/vv78-at49.


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:Public (worldwide access)
Research Advisor(s):
  • Thorne, Kip S.
Group:TAPIR, Astronomy Department
Thesis Committee:
  • Blandford, Roger D. (chair)
  • Cowan, Eugene W.
  • Wise, Mark B.
  • Thorne, Kip S.
Defense Date:7 November 1983
Funding AgencyGrant Number
Record Number:CaltechTHESIS:09012017-133647841
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter II. adapted for Chapter III.
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10410
Deposited By: Benjamin Perez
Deposited On:06 Sep 2017 20:23
Last Modified:16 Apr 2021 23:13

Thesis Files

PDF - Final Version
See Usage Policy.


Repository Staff Only: item control page