Basic properties of toroidal structures in Kerrde Sitter backgrounds
Abstract
Perfect fluid tori with uniform distribution of the specific angular momentum orbiting the Kerrde Sitter black holes or naked singularities are studied. Closed equipotential surfaces corresponding to stationary toroidal discs are allowed only in the spacetimes admitting stable circular geodesics. The last closed surface crosses itself in the cusp(s) enabling outflow(s) of matter from the torus due to the violation of hydrostatic equilibrium. The repulsive cosmological constant, Λ > 0, implies the existence of the outer cusp (with a stabilizing effect on the tori because of excretion, i.e., outflow of matter from the torus into the outer space) and the strong collimation of open equipotential surfaces along the rotational axis. Both the effects take place nearby socalled static radius where the gravitational attraction is just balanced by the cosmic repulsion. The plusfamily discs (which are always corotating in the blackhole backgrounds but can be counterrotating, even with negative energy of the fluid elements, in some nakedsingularity backgrounds) are thicker and more extended than the minusfamily ones (which are always counterrotating in all backgrounds). If parameters of the nakedsingularity spacetimes are very close to the parameters of extreme blackhole spacetimes, the family of possible disclike configurations includes members with two isolated discs where the inner one is always a counterrotating accretion disc. Mass estimates for tori with nonrelativistic adiabatic equation of state give limits on their central massdensity, for which the approximation of test fluid is adequate.
 Publication:

Albert Einstein Century International Conference
 Pub Date:
 November 2006
 DOI:
 10.1063/1.2399656
 arXiv:
 arXiv:astroph/0605094
 Bibcode:
 2006AIPC..861..770S
 Keywords:

 04.70.Bw;
 97.60.Lf;
 98.80.Es;
 04.20.Dw;
 Classical black holes;
 Black holes;
 Observational cosmology;
 Singularities and cosmic censorship;
 Astrophysics
 EPrint:
 Updated version of the Section talk at Albert Einstein Century International Conference at Palais de l'Unesco, Paris, France, 1823 July, 2005