Publication date: Nov 2009
Abstract:
Pseudo-Newtonian gravitational potential introduced in spherically
symmetric black-hole spacetimes with a repulsive cosmological constant
is tested for equilibrium toroidal configurations of barotropic perfect
fluid orbiting the black holes. Shapes and potential depths are
determined for the marginally stable barotropic tori with uniform
distribution of specific angular momentum, using both the pseudo-
Newtonian and fully relativistic approach. For the adiabatic
(isoentropic) perfect fluid, temperature profiles, mass-density and
pressure profiles and total masses of pseudo-Newtonian and relativistic
tori are compared providing important information on the relevance of
the test-disc approximation in both the approaches. It is shown that the
pseudo-Newtonian approach can be precise enough and useful for the
modelling of accretion discs in the Schwarzschild-de Sitter spacetimes
with the cosmological parameter y = ΛM2/3 lsim
10-6. For astrophysically relevant black holes with y <
10-25, this statement is tested and shown to be precise in
few per cent for both accretion and excretion tori and for the
marginally bound, i.e. maximally extended, tori allowing simultaneous
inflow to the black hole and outflow to the outer space.
Authors:
Stuchlík, Zdeněk; Slaný, Petr; Kovář, Jiří;