CYGNUS-X-3 LIGHT-CURVE MODEL IN THE TEV ENERGY REGION

We consider a close binary system containing a compact object and suggest that very high-energy (VHE) gamma-rays are produced near this object. In such a system the VHE gamma-rays have to interact with soft photons around the companion star by gammagamma-->ee reactions. These soft photons have a radial distribution, so the VHE gamma-rays will reach the observer when their source lies between the companion star and the observer, because the reaction is impossible if the angle between the momenta of soft photon and gamma-quantum is small. In this model the VHE gamma-ray light curve has a sharp maximum at the orbital phase region 0.2-0.8 for orbits with various orientations and eccentricities. Our calculations show that for the orbital parameters of Cygnus X-3 the light-curve maximum occurs at phase almost-equal-to 0.6, which is in agreement with recent experimental data.