The effect of radiation pressure on accretion disks around black holes

Steady-state disk accretion on to a black hole is studied for high accretion rates, where the dynamic effect of radiation pressure is important. The rotation of the disk is not assumed to be Keplerian, but is considered as an unknown in the Newtonian dynamic equation. The problem is reduced to a set of two differential equations which are solved numerically. It is found that steady-state solutions without mass-outflow exist for accretion rates greater than the critical rate. The radiated luminosity, however, is always of the order of the Eddington luminosity. For increasing accretion rates, the kinetic energy swallowed by the hole and the size of the radiating region increase