Search of signatures for pair production and reflection in high energy X ray spectra of active galaxies

The observations of active galaxies, using the X-ray detector HEXE were evaluated, and the measured spectra were compared with the predictions of astrophysical plasma models. Particular attention was given to the effects of electron positron pair production by photon collision and reflection of a primary continuum on a colder matter, in particular an accretion disk. The objects considered were the quasar 3C 273, the Seifert galaxy NGC 4151 and the radiogalaxy CEN A. A joint evaluation, using data of the Japanese X-ray satellite GINGA showed that the share of a reflective component in the spectra of 3C 273 and NGC 4151 was very low. It was shown that only NGC 4151 could be described, using a pair cascade model.