γ-Ray emission from a pulsar outer magnetosphere Original Research Article

We study the structure of a stationary outer gap accelator around an oblique rotator. Near to the light cylinder, pulsar wind may bring about the charge depletion, which causes a large electric field along the magnetic field lines. This longitudinal electric field accelerates migratory electrons and positrons to ultra-relativistic energies. These relativistic particles radiate γ-ray photons by curvature radiation. These γ-ray photons produce yet more radiating particles by colliding with surface blackbody X-ray photons, leading to a pair production cascade in the gap. The replenished charges partially screen the longitudinal electric field, which is self-consistently solved together with the distribution of e±ʹs and γ-ray photons. We find the γ-ray spectra as a function of the blackbody temperature and the inclination angle between the rotational and magnetic axes, and apply the results to PSR B1706-44 to predict that the blackbody temperature of its unobserved X-ray radiation is about 85 eV.