Black-hole electrodynamics

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6351683

Macdonald, D A

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 flat-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 develpoed. 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.

• Research Organization: California Inst. of Tech., Pasadena (USA)
• OSTI ID: 6351683
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BLACK HOLES
COSMIC RADIO SOURCES
EARTH ATMOSPHERE
ELECTRODYNAMICS
ELECTROMAGNETIC FIELDS
FOUR-DIMENSIONAL CALCULATIONS
GLOBAL ANALYSIS
MAGNETOSPHERE
MATHEMATICS
QUASARS
SPACE-TIME