A combined model for the X-ray to gamma-ray emission of Cygnus X-1

We use recent data obtained by three (OSSE, BATSE, and COMPTEL) of four ins truments on board the Compton Gamma Ray Observatory (CGRO) to construct a m odel of Cyg X-1 that describes its emission in a broad energy range, from s oft X-rays to MeV gamma-rays, self-consistently. The gamma-ray emission is interpreted to be the result of Comptonization, bremsstrahlung, and positro n annihilation in a hot, optically thin, and spatially extended region surr ounding the whole accretion disk. For the X-ray emission, a standard corona -disk model is applied. We show that the Cyg X-1 spectrum accumulated by th e CGRO dinstruments during a similar to 4 year time period between 1991 and 1995, as well as the HEAO 3 gamma(1) and gamma(2) spectra, can be well rep resented by our model. The derived parameters match the observational resul ts obtained from X-ray measurements.