Effect of dark energy models on the energy content of charged and rotating black holes

The energy content of the charged-Ken (CK) spacetime surrounded by dark energy (DE) is investigated using approximate Lie symmetry methods for the differential equations. For this, we consider three different DE scenarios: cosmological constant with an equation of state parameter omega(c) = -1, quintessence DE with an equation of state parameter omega(q) = -2/3, and a frustrated network of cosmic strings with an equation of state parameter omega(n) = -1/3. To study the gravitational energy of the CK black hole surrounded by the DE, we explore the symmetries of the 2nd-order perturbed geodesic equations. It is noticed, for all the values of omega, the exact symmetries are recovered as 2nd-order approximate trivial symmetries. These trivial approximate symmetries give the resealing of arc length parameter s in this spacetime which indicates that the energy in the underlying spacetime has to be resealed by a factor that depends on the black hole parameters and the DE parameter. This resealing factor is compared with the factor of the CK spacetime found in [Hussain et al. Gen. Relativ. Gravit. (2009)] and the effects of the DE on it are discussed. It is observed that for all the three values of the equation of state parameter omega, the effect of DE results in decreased energy content of the black hole spacetime, regardless of values of the charge Q, spin a and the DE parameter alpha. This reduction in the energy content due to the involvement of the DE favours the idea of mass reduction of black holes by accretion of DE given by [Babichev et al. Phys. Rev. Lett. (2004)].

Automated summary

Using approximate Lie symmetry methods, the energy content of the charged-Ken (CK) spacetime surrounded by dark energy (DE) is investigated. The involvement of DE leads to a reduction in the energy content of the black hole spacetime.