Multipole moments in general relativity and dynamical perturbations of black-hole magnetospheres

Miscellaneous · Mon Jan 01 00:00:00 EST 1990

OSTI ID:6690284

Zhang, Xiaohe

In part 1 the generic, vacuum, dynamical gravitational field of the exterior universe in the vicinity of a freely moving body is expanded in positive powers of the distance r away from the body's spatial origin. The expansion coefficients, called external multipole movements, are defined covariantly in terms of the body's central world line. The expansion is used to derive higher-order corrections to previously known laws of motion and precession for black holes and other bodies. In part 2, the interaction of magnetohydrodynamic (MHD) waves in a black-hole magnetosphere with the dragging of inertial frames effect of the holes effect of the hole's rotation is studied. The laws of perfect general relativistic magnetohydrodynamics (GRMHD) are rewritten in 3 + 1 language in a general spacetime, and the GRMHD equations are reduced to a set of algebraic equations for stationary spacetimes and MHD flows with one arbitrary spatial symmetry. Then in a model spacetime with two spatial symmetries, which captures the key features of the Kerr geometry, the Fourier-analyzed GRMHD equations are derived which govern weak, linearized perturbations of a stationary magnetosphere with outflowing jet. These equations are subsequently solved numerically. It is found that when an oscillatory external force is applied to the region of the magnetosphere where plasma (e+ e-) is being created, the magnetosphere responds especially strongly at a particular, resonant, driving frequency. The magnetosphere of a rotating black hole, when perturbed by nonaxisymmetric magnetic fields, might exhibit an analogous resonance. If so then the hole's outflowing jet might be modulated at resonant frequencies omega is approx. = (m/2)Omega{sub H} where m is an integer and Omega{sub H} is the hole's angular velocity.

• Research Organization: California Inst. of Tech., Pasadena, CA (USA)
• OSTI ID: 6690284
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BLACK HOLES
DISTURBANCES
RELATIVITY THEORY
MULTIPOLES
ANGULAR VELOCITY
FOURIER ANALYSIS
GRAVITATIONAL FIELDS
HYDROMAGNETIC WAVES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
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