Hard Spectral Tails in Magnetars

Abstract

Pulsed non-thermal quiescent emission between 10 keV and around 150 keV has been observed in ∼ 10 magnetars. For inner magnetospheric models of such hard X-ray signals, resonant Compton upscattering of soft thermal photons from the neutron star surface is the most efficient radiative process. We present angle-dependent hard X-ray upscattering model spectra for uncooled monoenergetic relativistic electrons. The spectral cut-off energies are critically dependent on the observer viewing angles and electron Loren…