2000MNRAS.317...97B

In the advent of next generation gamma-ray missions, we present general properties of spectral features of high-energy emission above 1MeV expected for a class of millisecond, low magnetic field (∼10⁹G) pulsars. We extend polar-cap model calculations of Rudak & Dyks by including inverse Compton scattering events in an ambient field of thermal X-ray photons and by allowing for two models of particle acceleration. In the range between 1MeV and a few hundred GeV, the main spectral component is the result of curvature radiation of primary particles. The synchrotron component arising from secondary pairs becomes dominant only below 1MeV. The slope of the curvature radiation spectrum in the energy range from 100MeV to 10GeV strongly depends on the model of longitudinal acceleration, whereas below ∼100MeV all slopes converge to a unique value of 4/3 (in a νF_ν convention). The thermal soft X-ray photons, which come either from the polar cap or from the surface, are Compton upscattered to a very high energy domain and form a separate spectral component peaking at ∼1TeV. We discuss the observability of millisecond pulsars by future high-energy instruments and present two rankings relevant for GLAST and MAGIC. We point to the pulsar J0437-4715 as a promising candidate for observations.