The origin of X-rays and Gamma-rays from collapsed objects

In this paper we review our studies on relativistic plasmas, spherically and adiabatically accreting onto collapsed objects, where pi(0), produced by proton-proton collisions, decay into gamma-rays and the electron-proton bremsstrahlung produces X-rays. In particular we discuss the thermal and non-thermal models with applications to 3C 273 and Geminga. After the discovery of beamed sources, we have studied also the interactions of relativistic electron-proton beams,ejected from collapsed objects, with the surrounding matter and/or radiation. Therefore we discuss the photon energy spectra from Inverse Compton Scattering (ICS) of relativistic electron-beams with an arbitrary background radiation and the photon energy spectra from proton-proton interactions via pi(0)-decay for relativistic proton-beams. In particular we discuss the derived theoretical spectra succesfully used to fit the experimental data of Cg X-1.