Electrodynamics of the event horizon

Journal Article · Fri Dec 15 04:00:00 EST 1989 · Physical Review, D (Particles Fields); (USA)

DOI:https://doi.org/10.1103/PhysRevD.40.3834· OSTI ID:6982414

Punsly, B ^[1]; Coroniti, F V ^[2]

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1. Department of Physics, University of California, Los Angeles, California 90024-1547 (USA)
2. Department of Astronomy and Department of Physics, University of California, Los Angeles, California 90024-1547 (USA)

This paper is an investigation of the electrodynamics of the event horizon of a Kerr black hole. It is demonstrated that the event horizon behaves quite generally as an asymptotic vacuum infinity for axisymmetric, charge-neutral, accreting electromagnetic sources. This is in contrast with the general notion that the event horizon can be treated as an imperfect conductive membrane with a surface impedance of 4{pi}/{ital c}. The conductive-membrane model has been incorporated into the more sophisticated membrane paradigm of Thorne, Price, and Macdonald by supplementing the model with the full equations of general relativity. In certain situations (in particular those of astrophysical interest), the conductive-membrane interpretation forms the appropriate set of pictures and images in the membrane paradigm. In this paper we reevaluate the specific gedanken experiments that were originally used to motivate the paradigm. We find that great care must be exercised if the detailed interaction of a black hole's external gravitational field with a magnetized plasma is modeled by the electrodynamics of the conductive horizon membrane. For ingoing flows of plasma or electromagnetic waves (when the hole is passively accepting information), the interpretation of the horizon as a vacuum infinity is equivalent to an imperfect conductor with a surface impedance of 4{pi}/{ital c} (the impedance of the vacuum). In situations when an imperfect conductor should radiate information (such as a Faraday wheel) the event horizon cannot, since it is an infinity. The event horizon does not behave quite generally as an imperfect conductor, but has electrodynamic properties unique to itself.

• OSTI ID: 6982414
• Journal Information: Physical Review, D (Particles Fields); (USA), Journal Name: Physical Review, D (Particles Fields); (USA) Vol. 40:12; ISSN 0556-2821; ISSN PRVDA
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BLACK HOLES
DIFFERENTIAL EQUATIONS
ELECTRODYNAMICS
ELECTROMAGNETIC RADIATION
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