Braking of electrons in pulsar magnetospheres by Compton scattering in thermal radiation fields

Electrons accelerated at the polar cap of a pulsar lose energy by interactions with the thermal photospheric radiation. Using Michel’s acceleration model (1974) we present an analytical treatement of these braking processes taking into account curvature radiation as well as resonant and non–resonant inverse Compton scattering and the distribution of the thermal photons originating from the polar cap. Results are obtained for a wide range of pulsar parameters. It turns out that for photospheric temperatures below kT ∼= 100 eV and polar magnetic fields below B ∼= 1012.5 Gauss braking by inverse Compton scattering has negligible influence on the end energy of the electrons around the polar axes. For magnetic field strength between 1012.5 and 1013.5 Gauss the energy loss is significant but depends on the pulsar rotation period. In the case of very high temperatures such as kT = 1 keV the energy loss is dramatic within a wide range of magnetic field strengths. Millisecond pulsars are not affected.