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Astron. Astrophys. 363, 425-439 (2000)


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Equilibrium configurations of perfect fluid orbiting Schwarzschild-de Sitter black holes

Z. Stuchlík, P. Slaný  * and S. Hledík

Silesian University, Department of Physics, Faculty of Philosophy and Science, Bezruovo nám. 13, Opava, Czech Republic (zdenek.stuchlik@fpf.slu.cz; petr.slany@vsb.cz; stanislav.hledik@fpf.slu.cz)

Received 30 May 2000 / Accepted 15 September 2000

Abstract

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.

Key words: accretion, accretion disks – black hole physics – gravitation – relativity – galaxies: quasars: general

* Present address: Technical University at Ostrava, Department of Physics, Faculty of Mining, Ostrava, Czech Republic

Send offprint requests to: Z. Stuchlík

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000

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