Publication date: Feb 2017
Abstract:
Quintessential dark energy with density ρ and pressure p is governed by
an equation of state of the form p=ωqρ with the
quintessential parameter ω_qin (-1;-1/3). We derive the geometry of
quintessential rotating black holes, generalizing thus the Kerr
spacetimes. Then we study the quintessential rotating black hole
spacetimes with the special value of ωq = -2/3 when the
resulting formulae are simple and easily tractable. We show that such
special spacetimes can exist for the dimensionless quintessential
parameter c < 1/6 and determine the critical rotational parameter
a0 separating the black hole and naked singularity spacetime
in dependence on the quintessential parameter c . For the spacetimes
with ωq = -2/3 we give all the black hole characteristics and
demonstrate local thermodynamical stability. We present the integrated
geodesic equations in separated form and study in details the circular
geodetical orbits. We give radii and parameters of the photon circular
orbits, marginally bound and marginally stable orbits. We stress that
the outer boundary on the existence of circular geodesics, given by the
so-called static radius where the gravitational attraction of the black
hole is balanced by the cosmic repulsion, does not depend on the
dimensionless spin of the rotating black hole, similarly to the case of
the Kerr-de Sitter spacetimes with vacuum dark energy. We also give
restrictions on the dimensionless parameters c and a of the spacetimes
allowing for existence of stable circular geodesics. Finally, using
numerical methods we generalize the discussion of the circular geodesics
to the black holes with arbitrary quintessential parameter
ωq.
Authors:
Toshmatov, Bobir; Stuchlík, Zdeněk; Ahmedov, Bobomurat;