Theoretical study of [gamma]-ray emissions from pulsars

Abstract

In previous study, a three-dimensional two-layer outer gap model was proposed to explain the third peak in the light curve of Vela pulsar and could simulate the phase-resolved spectrum. After being applied to several different pulsars, it was discovered that there exist some deviations between the simulation results and the observed spectrum. Considering the outer gap structure may differ with time, the model then has been further developed into a non-stationary three-dimensional outer gap model. In this model, the outer gap is not stationary. The parameters in the stationary three-dimensional two-layer outer gap model have been assigned a power-law and calculate the weighted spectrum. Using this model, we found out that this model is available for some pulsars, but for pulsars like Geminga, it was still hard to explain the high energy part of its spectrum.

An Inverse-Compton Scattering component has been added into the model to find out if it would _t the high energy spectrum of Geminga pulsar. The IC scattering happens between soft photons (radio) and ultra-relativistic particles in the outer gap. This component can provide sufficient GeV photons in the outer gap, according to our study.