THE SOURCE OF TEV GAMMA-RAYS IN CEN X-3 AND VELA X-1

An experimentally verifiable model is developed to explain the discrep ancy between detected TeV gamma-ray pulsed periods and neutron star sp in periods in X-ray binary systems. It assumes that the TeV gamma-rays are produced at the X-ray period and not on the neutron star itself, but somewhere else in the orbital plane. It was successfully applied t o both Cen X-3 and Vela X-1. In the case of Cen X-3, an emission regio n was identified, with a 99.5% significance. This region trails the ne utron star by 70 degrees and is situated between the neutron star orbi t and the companion. For Vela X-1 an emission region outside the orbit of the neutron star was found, with a probability for chance occurren ce of 4 x 10(-5). This region leads the neutron star by 90 degrees. Th ese detections were used to illustrate the characteristics of the mode l, especially parameters determining its applicability and possible li mitations. (C) 1997 Elsevier Science B.V.