The pulse-phase dependence of the spectrum of GX 301-2

Abstract

Observations of the dependence of the X-ray spectrum of GX 301-2 on pulse phase are presented. The spectral parameters power-law spectral index, e-folding energy, and column density exhibit clear pulse-phase dependencies. The spectral index phase dependence changes between observations with different intensity. The spectral index also has an asymmetric dependence on pulse phase. The e-folding energy shows a hardening of the high-energy X-ray spectrum toward pulse maximum, in agreement with theoretical pulsar spectrum calculations. The column density increases at phases away from pulse maximum, which is consistent with being caused by scattering in the circumstellar matter. 14 refs.