Geminga: origins of its X-ray and gamma-ray emission

The ratio of X-ray to γ-ray emission from the Geminga pulsar is explained, independently of the distance to the pulsar, by Arons’ model for the production of relativistic particles near the pulsar surface at the polar caps. Polar cap heating by both reversed particles and their curvature radiation is able to explain the observed ratio of soft to hard X-ray components. This model predicts the distance to Geminga as $$D\simeq 20\enspace \text {pc} \enspace (4\pi/\Omega)^{1/4},\enspace \text {where} \enspace \Omega,$$ the emission solid angle, may differ from 4π by a factor of 2 – 3 or so.