particles at the inner edge, placing the accretion system around a rapidly rotating Kerr black hole. They found that for particles around the innermost stable circular orbit the effect of radiation becomes almost entirely azimuthal and that, interestingly and contrary to a standard intuition, it rather changes from [*drag*]{} to acceleration. This should enhance the efficiency of a “cosmic battery" mechanism in which the radiation push might trigger the jet outflows indirectly, through the production of magnetic field.

We would like to compare these various results (especially those of @VokrouhlickyK-91) with what can be found using the approach we have taken in previous papers. Restricting to the Schwarzschild case for simplicity now, in Section \[flux\] we [*prescribe*]{} the radiative flux to be emanating perpendicularly from the equatorial plane (where the thin accretion disc is imagined to lie) and study its properties, and then its interaction with the test particles in Section \[interaction\]. Then in Section \[approximation\] we suitably approximate the photon trajectories, choose the equatorial energy-density profile of the flux and extend it off the equatorial plane by approximating the conservation laws which govern its behavior. Then we add the contributions from two opposing radiation streams which—due to the symmetry—pass 