Pulsed gamma rays from Geminga.

The pulsed γ-ray spectrum from Geminga has been obtained from COS-B observation. The authors fit the pulsed spectrum by both the outergap and polar gap models and conclude that only the outergap model can explain the observed spectrum. They suggest that the pulsed γ-rays from Geminga are emitted by the primary e^± which are accelerated in the outer magnetospheric gap. If the observed X-ray from Geminga result from the stellar heating by these primary electrons/positrons, it is argued that this is a common phenomenon for all pulsars with an outergap. Its power is 1.3×10³¹P^-2B₁₂erg s^-1.