Electromagnetic jets in pulsar magnetospheres and near magnetized accretion disks

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6486642

Sulkanen, M E

The author studied the structure of the electromagnetic fields that surround a rotating, magnetized neutron star or that may be in and near the accretion disk of an active galactic nucleus. He uses the method developed for time-independent axisymmetric fusion plasma equilibria the Grad-Shafranov equation. This procedure allows one to apply a powerful result from fusion plasma equilibria to constrain the form of the magnetic helicity for the configuration, Taylor's hypothesis. This removes an indeterminacy from the pulsar equation that has plagued all earlier attempts to find a unique equation to describe the fields. The pulsar equation is fixed to be a piecewise linear partial differential equation with a class of solutions that include self-collimated electromagnetic jets along the rotation axis of the star. These jets carry energy, angular momentum, and electric current away from the star. A finite-difference scheme is employed to solve for the entire field structure for these jet-magnetospheres. For the structure of the accretion disk fields, he first develops the formalism to describe the equilibria of a thin, viscous, resistive, and non-relativistic accretion disk, leading to simplified equations for the poloidal and toroidal magnetic field. He treats the coronal plasma that surrounds the disk like the magnetospheric plasma of the pulsar, and find a pulsar equation that determines the fields there. A Green's function method is used to determine the far-field solution for the coronal fields. Energy conservation for the disk-jet system yields a global consistency condition which restricts the amount of gravitational accretion power than can be carried away by the jets for a given field symmetry.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 6486642
• 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
ACCRETION DISKS
ANGULAR MOMENTUM
ATMOSPHERES
COSMIC RADIO SOURCES
CURRENTS
DIFFERENTIAL EQUATIONS
ELECTRIC CURRENTS
ELECTROMAGNETIC FIELDS
ENERGY LOSSES
EQUATIONS
EQUILIBRIUM
FINITE DIFFERENCE METHOD
ITERATIVE METHODS
LOSSES
NEUTRON STARS
NUMERICAL SOLUTION
PARTIAL DIFFERENTIAL EQUATIONS
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLASMA JETS
PULSARS
STARS
TIME DEPENDENCE