Periodic Emission of Gamma-Rays in Binary Stars

Abstract

In this paper we search for an orbital modulation of the VHE [gamma]-ray flux in LS 5039, a High Mass X-ray Binary that consists of a compact object in an 3.9 days orbit around a massive star. For this purpose we apply to archive HESS data of LS 5039 two methods: Least-Squares Spectral Analysis (LSSA) or Lomb-Scargle test, which has been proved effective in this task previously, and Period Determination Using Phase Dispersion Minimization (PDM). We'll see that both methods verify this periodic modulation and that it matches the orbital period of the binary system.