High‐Energy Radiation from Rapidly Spinning Pulsars with Thick Outer Gaps

Abstract

We propose a self-consistent mechanism to estimate the size of the acceleration region in the outer magnetosphere of pulsars (outer gap) and calculate the high-energy radiation produced by the synchrocurvature mechanism from the outer gap. We find that a power-law energy distribution of the accelerated particles can be obtained if the outer gap is thick enough that E ˙B hat inside the gap can be approximately proportional to ( Omega r/c)1/2B(r). We apply our model to explain X-rays and gamma -rays from Geminga and PSR B1055-52, whose outer gaps may occupy ~70% of the outer magnetosphere region. If the radius of curvature near the light cylinder of the medium outer gap is larger than the dipolar structure, then perhaps this model may also apply to PSR B1951+32, PSR B1706-44, and others.