S. Gupta, and M. Böttcher
Astrophysical Journal, submitted (2007)
HESS has recently detected Very High Energy (VHE) gamma-ray emission and its orbital modulation for the high mass X-ray binary and microquasar candidate LS 5039. Part, but not all of this orbital modulation can be attributed to the gamma-gamma absorption of the VHE gamma-rays in the intense photon field of the stellar companion. We have applied a time-dependent leptonic model incorporating a full Klein-Nishina treatment of the Compton scattering as well as the angle dependence of the stellar radiation field to the broadband spectral energy distribution of LS 5039. We suggest that a modulation in the injection spectral index and the electron injection luminosity in addition to the gamma-gamma absorption might be a possible cause for the observed orbital modulation of the TeV flux and spectral shape. We do a detailed parameter study of various physical properties of the system to see their signature on the X-ray Hardness Intensity Diagrams (HID)s and light curves, predicting spectral hysteresis features, giving us an insight into the individual emission mechanisms in X-rays energies.