Electrons accelerated to relativistic energies in pulsar magnetosphere
s will Compton scatter surface thermal emission and nonthermal optical
, UV, and soft X-ray emission to gamma-ray energies, thereby initiatin
g a pair cascade through synchrotron radiation and magnetic pair produ
ction. This process is proposed as the origin of the high-energy radia
tion that has been detected from six isolated pulsars. We construct an
analytic model of magnetic Compton scattering near the polar cap of i
solated pulsar magnetospheres and present approximate analytic derivat
ions for scattered spectra, electron energy-loss rates, and photon lum
inosities. A Monte Carlo simulation is used to model the pair cascade
induced by relativistic electrons scattering photons through the cyclo
tron resonance. For simplicity, the primary electrons are assumed to b
e monoenergetic and the nonresonant emission is omitted. Assuming that
the angle phi(B) between the magnetic and spin axes is approximately
equal to the polar-cap angle theta(pc), this model can produce both do
uble-peaked and broad single-peaked pulse profiles and account for the
trend of harder gamma-ray spectra observed from older pulsars.