Axially symmetric steady-state flows in the vicinity of a Kerr black hole and the nature of the activity of galactic nuclei
V.S. Beskin a
a Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
A generalization of the force-free equation describing steady-state axially symmetric flows in the vicinity of a Kerr black hole is carried out to the case of ideal magnetohydrodynamics. It is shown how this equation changes from an elliptic to a hyperbolic type in the vicinity of the horizon. The limits of applicability of the approach under discussion are examined for different astrophysical sources. It is shown that a high photon density strongly restricts the limits of applicability of the MHD approach.