The Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray|
Observatory has detected pulsed signals from at least six rotation-powered pulsars.
Theoretical attempts to explain these high-energy emissions have concentrated on
two scenarios: The slot-gap model in which particle acceleration zone (gap) resides
very close to the so-called 'last-open field lines' and the outer-gap model in which
the gap is located in the outer magnetosphere, typically a few hundred neutron-star
radii away from the star. In both models, so far, to solve the gamma-ray emission,
they have assumed the gap position and geometry, magnetic-field-aligned electric
field strength, as well as the spatial density and the energy distribution of
electrons and positrons. In this talk, I will talk about my new attempt to
solve these quantities with a few assumptions as possible from the first principles
in the 3-D pulsar magnetosphere, and demonstrate that the outer-gap model can
reproduce the gamma-ray observations while the slot-gap models cannot.
I will give some prediction of the potential pulsars to be detected with
the Fermi Gamma-ray Space Telescope, which was launched June 2008.