Propagation of gamma-rays in massive binary Cen X-3: Interaction of cascade gamma-rays with the massive star

We consider the propagation of very high energy (VHE) gamma-rays in the radiation field of the massive star of binary system Cen X-3. VHE gamma-rays or electrons, injected by the compact object close to the surface of a massive companion, develop inverse Compton e(+/-) pair (ICS) cascades. Based on the Monte Carlo simulations, we obtain the fraction of secondary cascade photons which collide with the surface of the massive companion in Cen X-3 system. The distribution of photons falling on the surface of the massive star is investigated. These photons interact with the atmosphere of the star and should excite different gamma-ray lines (nuclear, e(+/-) annihilation line). We estimate that these gamma-ray lines can be likely detected by the INTEGRAL telescopes.