Spinning test particles in the field of a black hole.
Abstract
The motion of spinning test particles in the gravitational field of a rotating black hole is analyzed in the poledipole approximation using the Papapetrou equations in the special case where the equations are exactly solvable and the particle trajectories obtained do not have parallel momentum and velocity. Attention is restricted to the equatorial plane of the Kerr metric, with the spin perpendicular to this plane. It is shown that the conserved quantities associated with the two Killing vectors give sufficient first integrals for a complete solution to be determined. The behavior of particle velocity in various orbits is examined, and the limits of validity of the poledipole approximation are evaluated. It is found that a black hole tends to repel particles with sufficiently high spin if the particle spin and blackhole rotation have the same sign. The problem of energy extraction from the innermost stable circular orbits is considered. The behavior of these orbits is shown to indicate that particles will be separated according to spin sign in the process of disk accretion in the equatorial plane and that the fraction of energy 'at infinity' that can be extracted from an accreting particle with spin opposite to the blackhole rotation may be as high as 100 per cent.
 Publication:

Nuovo Cimento B Serie
 Pub Date:
 August 1976
 DOI:
 10.1007/BF02728614
 Bibcode:
 1976NCimB..34..365T
 Keywords:

 Black Holes (Astronomy);
 Equatorial Orbits;
 Gravitational Effects;
 Particle Motion;
 Particle Trajectories;
 Relativity;
 Astrophysics;
 Equations Of Motion;
 Vector Spaces;
 Astrophysics