Effects of radiation damping on particle motion in pulsar vacuum fields

Abstract

The effects of radiation reaction on the motion of charged particles are studied in strong electric and magnetic fields with special attention to the vacuum near-field region of an oblique rotator. For strong radiation damping a local velocity field is derived from the Lorentz-Dirac equation, which efficiently describes the motion of electrons and positrons in the whole range of typical pulsar parameters. The velocity field makes it possible to define regions in the inner magnetosphere, where particle trapping occurs due to the radiation losses. By numerical integration of particle trajectories from the pulsar surface, regions around the magnetic poles are found which are defined by particle emission into the wave zone. The shapes of the escape regions on the pulsar surface are determined to a considerable extent by the presence of the accumulation regions.