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    Basic properties of toroidal structures in Kerr-de Sitter backgrounds

    Zdeněk Stuchlík · 01 listopadu, 2006 · Fyzika · 0 comments
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    Publication date: Nov 2006

    Abstract:
    Perfect fluid tori with uniform distribution of the specific angular
    momentum orbiting the Kerr-de 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 so-called static radius where the
    gravitational attraction is just balanced by the cosmic repulsion. The
    plus-family discs (which are always corotating in the black-hole
    backgrounds but can be counterrotating, even with negative energy of the
    fluid elements, in some naked-singularity backgrounds) are thicker and
    more extended than the minus-family ones (which are always
    counterrotating in all backgrounds). If parameters of the
    naked-singularity spacetimes are very close to the parameters of extreme
    black-hole spacetimes, the family of possible disc-like 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
    mass-density, for which the approximation of test fluid is adequate.

    Authors:
    Stuchlík, Zdeněk; Slaný, Petr;

    http://adsabs.harvard.edu/abs/2006AIPC..861..770S

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