Model Spectra of Rotation Powered Pulsars in the INTEGRAL Range

Abstract

The energy range of IBIS is a promising ground for testing mutual relations of distinct components expected in the spectra of high-energy radiation from rotation powered pulsars. According to some polar-cap models two such components - due to curvature and synchrotron emission - may contribute comparable amounts of power between 15 keV and 10 MeV (Rudak & Dyks 1999). Zhang & Harding (2000) argued recently for the inclusion of a third possible component, due to inverse Compton scattering (ICS) of soft thermal photons on secondary $\epm$-pairs. Here we present the results of Monte Carlo calculations of all three spectral components within a polar-cap model which allows for interactions of relativistic particles with the soft photons coming from the pulsar surface. For teragauss pulsars with the surface temperature of a few times 10^5 K the ICS component dominates the spectrum in the energy range below 10 MeV, and thus its presence increases the ratio of X-ray to gamma-ray luminosity (in comparison to the models ignoring the ICS on secondary $\epm$-pairs) to a level observed in the Vela pulsar.