Publication date: Nov 2000
The hydrodynamical structure of perfect fluid orbiting Schwarzschild-de
Sitter black holes is investigated for configurations with uniform
distribution of angular momentum density. It is shown that in the black-
hole backgrounds admitting the existence of stable circular geodesics,
closed equipotential surfaces with a cusp, allowing the existence of
toroidal accretion disks, can exist. Two surfaces with a cusp exist for
the angular momentum density smaller than the one corresponding to
marginally bound circular geodesics; the equipotential surface
corresponding to the marginally bound circular orbit has just two cusps.
The outer cusp is located nearby the static radius where the
gravitational attraction is compensated by the cosmological repulsion.
Therefore, due to the presence of a repulsive cosmological constant, the
outflow from thick accretion disks can be driven by the same mechanism
as the accretion onto the black hole. Moreover, properties of open
equipotential surfaces in vicinity of the axis of rotation suggest a
strong collimation effects of the repulsive cosmological constant acting
on jets produced by the accretion disks.
Stuchlík, Z.; Slaný, P.; Hledík, S.;