Energy and Angular Momentum Transport in Magnetohydrodynamical Accretion onto a Rotating Black Hole
Abstract
The rotating effects of a black hole on magnetohydrodynamical (MHD) accretion have been studied. The dynamical evolution of MHD accretion in Kerr spacetime was numerically calculated. A new calculation method is proposed, in which the fluid dynamics is solved in a frame with a starfixed coordinate, and the magnetic field is calculated in the locally nonrotating frame. We set the initial conditions of MHD accretion so that the magnetic field and fluid are homogeneous around a black hole and the fluid is static. We studied the inertiadominant case, i.e., the magnetic stress is weak compared with the inertia of the fluid. The transfer laws of the energy and angular momentum were investigated. MHD interaction in rotating spacetime produces angular momenta in the opposite direction, i.e., the direction of the angular momentum of the magnetic field is a counter rotating against a hole's spin, while the fluid rotates in the same direction as a hole. The spacetime rotation decreases the energyatinfinity for a magnetic field and increases the energyatinfinity for a fluid. A rapidly rotating black hole produces a negative energy region for a magnetic field near to the horizon. The functional relations of the angular momentum of the black hole, the strength of magnetic field, and the density of the fluid on the magnitudes of the transports are given.
 Publication:

Publications of the Astronomical Society of Japan
 Pub Date:
 April 1993
 Bibcode:
 1993PASJ...45..207Y
 Keywords:

 Active Galactic Nuclei;
 Angular Momentum;
 Black Holes (Astronomy);
 Magnetohydrodynamic Flow;
 Mass Transfer;
 Rotating Fluids;
 Energy Transfer;
 Interstellar Magnetic Fields;
 SpaceTime Functions;
 Astrophysics;
 ACTIVE GALACTIC NUCLEI;
 BLACK HOLES;
 MAGNETOHYDRODYNAMICS;
 NUMERICAL SIMULATION