On a model of steady-state accretion flow onto a balck hole in the mode of a thick disk with magnetic field

We show that the toroidal magnetic field in an axisymmetrical accretion flow can play the same role as angular momentum by preventing from fall of accreting material onto the centre of field. We use an assumption of axial symmetry of the flow, an assumption of smallness of angular momentum and an assumption of domination of toroidal component of the magnetic field. The latter condition is provided by the poloidal structure of currents, thus the disk is actually a closed solenoid. Averaging over vertical coordinate with the assumption of magnetohydrostatic equilibrium allows to reduce the system of MHD-equations to the system of ordinary differential equations for radial-dependent variables that converts the accretion model to the quasispherical one. The structure of the steady state flow is determined by two parameters. The first one is analogous to the Bondi parameter in the spherical accretion model without magnetic field, the other one specifies intensity of the magnetic field. We find the region with three singular points on a parameter plane. Two saddle-points meet the transonic transition. We also find the solution for a steady shock jump joining two transonic flows.