Numerical studies of the axisymmetric pulsar magnetosphere

Abstract

A numerical model based on the assumption that pulsars are spinning magnetized neutron stars is studied. A two-fluid model which includes inertial terms coupled self-consistently with Maxwell's equations is used. The case with aligned rotation and magnetic axes is examined on the assumption that the only source of charged particles is the star itself. It is found that under these conditions, the magnetic-field lines are closed everywhere, and the particles in the equatorial region close to the light cylinder reach sufficiently high energies to escape from the magnetosphere. With the Crab pulsar parameters, 1 by 10 to the 38th power ergs/sec are carried away by relativistic particles, and an equatorial region of high energy density is found near the light cylinder. It is tentatively concluded that the described behavior is due to the assumption regarding the source of particles which results in 100% charge separation and a space-charge-limited emission from the star. In this space-charge-limited regime, not enough current is available to open the field lines, but the electrostatic forces are large enough to force motion across them. An artificially large particle rest mass has been used in this paper to ensure a smoother transition between the nonrelativistic and highly relativistic regions of space.