In the case of low temperatures () of the hot thermal cap, for a wide range of magnetic field strengths B and rotation periods P, inverse Compton scattering (resonant and nonresonant) of thermal photons by accelerated electrons is not able to significantly lower the final maximum Lorentz factor of the electrons leaving the acceleration zone described by the model of Michel (1974). For (standard) pulsars with , temperatures around , and magnetic field strengths between and a substantial damping occurs. This effect extends over a wider range of magnetic field strengths in the case of .
The situation within the acceleration zone is more complicated. Here a large region exists, where electrons can not be accelerated above Lorentz factors of , but recover to high energies before they reach the end of the acceleration zone. Therefore, high end energies of the electrons near the theoretical maximum energy do not guarantee for a linear acceleration within the acceleration zone.
Although the cross section for non-resonant ICS is much lower than for the resonant ICS, neglecting the contribution of non-resonant ICS may lead to wrong results for parameter settings (e.g. and ) which are absolutely typical for standard neutron stars.
For millisecond pulsars no braking due to inverse Compton scattering occurs, as expected, as long as magnetic dipole fields are considered. The final maximum Lorentz factor as well as the intermediate Lorentz factors during acceleration are not affected by any significant damping except for the first few centimeters near the neutron star surface.
The results reported here concerning the energy loss due to ICS is found to remain valid up to a height of the inner magnetosphere of approximately one neutron star radius, independent of the choosen acceleration model.
© European Southern Observatory (ESO) 2000
Online publication: May 3, 2000