Hydrodynamics of black hole-accretion disk collision

The hydrodynamics of the collision of a supermassive (secondary) black hole and an accretion disk orbiting another supermassive (primary) black hole is investigated. An analytical theory of the hydrodynamical flows that are induced in the disk by the collision is constructed. Two-dimensional hydrodynamical simulations are performed for the case in which the black hole trajectory is perpendicular to the disk plane. It is shown that such a collision results in supersonic two-sided outflows ("fountains") of hot, optically thick, radiation-dominated gas from the disk. The spatial structure as well as the dynamics of these outflows is obtained numerically, giving good agreement with the results derived from the analytical theory. The estimated peak luminosity from the collision event is of the order of the Eddington luminosity for the secondary black hole.