The relativistic spherical accretion by black holes

The relativistic spherical accretion onto black holes is considered. It is shown that electron heat conductivity and ion viscosity increase the ion temperature by roughly two orders of magnitude over the electron temperature at Schwarzschild radius. As a result, the knee arise in gamma-radiation spectrum at 10–30 MeV. The role of magnetic field, electron-positron pairs production and generation of absorption lines in spectrum briefly discussed.