Equatorial circular orbits in Kerrantide Sitter spacetimes
Abstract
Equatorial circular orbits of test particles in the Kerrantide Sitter blackhole and nakedsingularity spacetimes are analyzed and their properties like the existence, orientation and stability are discussed. Due to the attractive cosmological constant (), all particles moving along equatorial orbits are still bound in the gravitational field of the central object. In general, there are two families of equatorial circular orbits. Particles moving along minusfamily orbits possess negative angular momentum and, thus, they are counterrotating from the point of view of the locally nonrotating frames (LNRF). Particles moving along plusfamily orbits possess, in most cases, positive angular momentum and belong to corotating particles from the point of view of the LNRF. Nevertheless, in stationary regions inside black holes and also near naked singularities with appropriately chosen value of the cosmological constant and rotational parameter , there are also counterrotating plusfamily circular orbits. Moreover, in spacetimes with , some of these orbits are characterized by negative specific energy, indicating the bounding energy of the particle, moving along such an orbit, higher than its rest energy. In blackhole spacetimes, all such orbits are radially unstable, but in nakedsingularity spacetimes, stable counterrotating orbits with negative specific energy exist.
 Publication:

General Relativity and Gravitation
 Pub Date:
 December 2013
 DOI:
 10.1007/s107140131606x
 Bibcode:
 2013GReGr..45.2611S
 Keywords:

 Kerrantide Sitter spacetime;
 Black hole physics;
 Naked singularities;
 Circular orbits