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When , inverse Compton emission will provide
the
primary spectrum to initiate the cascade, which then proceeds via
one-photon pair production and synchrotron radiation, similar to
the
curvature initiated cascades. ICPC models have been
investigated by
Dermer & Sturner (1994) and by Sturner et al.
(1995). The energy to
which the primary electrons are accelerated
is assumed to be that only of
the space-charge limited flow
potential, .
However, the energies required to radiate photons with energies up to
several GeV with Compton
scattering are much lower than for primary
curvature radiation.
The final -ray spectra
have power law indices that may be as
hard as in the
case of no cascading to with a
synchrotron photon cascade
contribution. Since pulsars with larger
will have softer
spectra, this model may also explain the
correlation of spectral hardness
with apparent age.
ICPC models cannot produce cascades several stellar radii above
the neutron
star surface in pulsars whose thermal X-ray emission
from a hot polar cap
dominates the non-thermal X-rays, because
the flux of soft photons decreases
rapidly with altitude. In order to
reproduce the widely separated
double-peaked profiles, these
models must require very small obliquities,
(Sturner & Dermer 1995).
Inverse-Compton induced pair cascades
Next: Outer Gap Models
Up: Polar Cap Models
Previous: Curvature radiation induced pair
BIBLIOGRAPHY