Abstract
Novel static black hole solutions with electric and magnetic charges are derived for the class of modified gravities: f({{{mathcal {R}}}})={{{mathcal {R}}}}+2beta sqrt{{{mathcal {R}}}}, with or without a cosmological constant. The new black holes behave asymptotically as flat or (A)dS space-times with a dynamical value of the Ricci scalar given by R=frac{1}{r^2} and R=frac{8r^2Lambda +1}{r^2}, respectively. They are characterized by three parameters, namely their mass and electric and magnetic charges, and constitute black hole solutions different from those in Einstein’s general relativity. Their singularities are studied by obtaining the Kretschmann scalar and Ricci tensor, which shows a dependence on the parameter beta that is not permitted to be zero. A conformal transformation is used to display the black holes in Einstein’s frame and check if its physical behavior is changed w.r.t. the Jordan one. To this end, thermodynamical quantities, as the entropy, Hawking temperature, quasi-local energy, and the Gibbs free energy are calculated to investigate the thermal stability of the solutions. Also, the casual structure of the new black holes is studied, and a stability analysis is performed in both frames using the odd perturbations technique and the study of the geodesic deviation. It is concluded that, generically, there is coincidence of the physical properties of the novel black holes in both frames, although this turns not to be the case for the Hawking temperature.
Highlights
The discovery of gravitational waves (GW) has shed light on a new possibility to probe the laws of physics in strong gravitational fields [1]
General relativity (GR) has been confirmed to a very good precision on weak gravitational field backgrounds [2]; the precise form of the anticipated, necessary modification of GR to deal with strong gravitational fields is not confirmed yet, different possibilities have been proposed
We have provided a detailed description of their physical properties, including their stability and causal structure, both in the Jordan and in the Einstein frames
Summary
The discovery of gravitational waves (GW) has shed light on a new possibility to probe the laws of physics in strong gravitational fields [1]. The aim of the present paper is to construct brand new black hole solutions, possessing electric and magnetic charge, within the family of f (R) modified gravities, to describe them in both the Jordan and the Einstein frames, and to study a number of their physical properties, by calculating associated thermodynamical quantities. 4, the same derivation is performed for the case of the Maxwell- f (R) theory involving a cosmological constant, and a new black hole solution is constructed, which behaves asymptotically as AdS or dS space. We are going to assume a particular form for the field Eq (4), with and without a cosmological constant, in order to be able to derive exact charged solutions asymptotically behaving as flat, respectively AdS/dS space-times
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
