Pulsars with strong magnetic fields: polar gaps, bound pair creation and nonthermal luminosities

The primary objective in this paper is to discuss how models of pulsar electrodynamics need to be modified when the magnetic field is strong enough for creation of bound pairs to dominate over the formation of free pairs. First, several preliminary aspects of the problem are discussed and it is demonstrated that the rate of injection of the primary particles depends on the properties of the matter at the surface of a magnetic neutron star. The particle outflow from the neutron star surface is discussed in Section 2. Particle acceleration and generation of curvature γ rays in the pulsar magnetospheres are described in Section 3. Propagation of γ rays, including photon splitting, and creation of electron-positron pairs in a strong magnetic field are discussed in Section 4. In Section 5, a polar-gap model is developed for pulsars with strong magnetic fields at their surface, Bs > 0 1 Bcr, and the maximum value of the nonthermal luminosity is estimated for such a pulsar. The interpretation of the observational data and some theoretical predictions on the nonthermal radiation of pulsars with Bs > 0 1 BCr are also given. 98 refs., 1 tab., 2 figs