The process of photon-splitting and its effect on pulsar emission: The analytic approach

Abstract

Magnetic photon splitting gamma --> gamma gamma, a quantum electrodynamic process that becomes important when magnetic field approaching the quantum critical value, B-c = 4.413 x 10(13) G, may have important effects on pulsar radio emission. According to the standard model, the pulsar radio emission is produced by coherent curvature radiation of a large amounts of e(+/-) pairs, which are thought to be generated by the pair creation process gamma + B --> e(+/-). However, if the magnetic field is strong enough, the photon splitting may dominate the pair creation process, then the amounts of e+/- pairs and the radio luminosity will be strongly suppressed and may be undetectable. Here we use the fitted analytical formula of the photon splitting attenuation coefficient to study the above process, and find that the photon splitting will strongly decrease the radio emission when B > 10(13) G. We also note that the photon splitting can strongly but not totally suppress the creation of pairs due to the diminishing dependence of B in the attenuation coefficient. We find that the ratio of the probability of a photon being absorbed by photon splitting to that by pair creation is no more than about six.