Equatorial Circular Orbits in the Kerr-Newman-de Sitter Spacetimes
Martin Petrasek
(Silesian University, Opava, Czech Republic)
Coauthor(s): Petr Slany, Zdenek Stuchlik
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We present influence of the cosmological constant on the character of the geodetical equatorial circular orbits in the rotating and charged Kerr-Newman black-hole and naked-singularity spacetimes. Conditions for the existence of geodesics are determined. Significant limits such as static radius, circular photon orbits are presented. We discuss existence, orientation and stability of the equatorial circular orbits. In the Kerr–Newman–de Sitter spacetime geometry the existence of two static radii implies different situation in both plus- and minus-family circular orbits in comparison with the Kerr–de Sitter spacetimes. Especially in naked singularity case, existence of the so called plus-family orbits is now restricted by the rotational parameter from above. Also, for some values of charge, cosmological parameter and rotational parameter, minus-family orbits exists not only between the outer static radius and minus-family circular photon orbit but also between the inner static radius and minus-family circular photon orbit.