High-energy gamma-ray absorption in relativistic magnetospheres

Calculations are made of the propagation of gamma-rays around neutron stars with a dipole magnetic field, including the effects of general relativity and the absorption by the one-photon magnetic pair production process, as a model for the high-energy transport in gamma-ray burst sources and pulsars. The paper discusses the escaping photon beam characteristics as seen by distant observers at different angles with respect to the magnetic axis, for radiation arising from the polar caps of neutron stars of varying degrees of compactness and surface field strengths. The observed beaming depends strongly on the surface field only up to B of about 0.05 times the critical field value, being essentially constant above the value 0.1. The gravitational light bending contributes significantly to broaden the beam profiles especially at low energies above threshold, being sensitive to the stellar radius to mass ratio.