Black Holes with Electric and Magnetic Charges in F(R)$F(R)$ Gravity

Abstract

We construct spherically symmetric and static solutions in Ffalse(Rfalse)$F(R)$ gravity coupled with electromagnetic fields. The solutions include new types of black holes with electric and magnetic charges. We show that the higher‐derivative terms make the curvature singularity much softer than that in the charged black holes in Einstein's general relativity. We calculate some thermodynamical quantities of the obtained black holes like entropy, Hawking radiation, and quasi‐local energy and we confirm that the black hole solutions satisfy the first law of thermodynamics. Finally, we study the stability analysis using the odd‐type mode and show that there are stable black hole solutions and the radial speed of the parity‐odd mode is unit, that is, the speed of light.

Existence of Dark Energy Stars within Lower Mass Gap in the Realm of f(Q)$f(Q)$ Gravity

“…The $$f(R)$$ theory of gravity is the most well‐known modified theory of gravity that replaces the Einstein‐Hilbert action with a more general action by assuming that the gravitational action is given by any arbitrary function of the Ricci scalar R . The modified gravities that attracted the researchers are $$f(R)$$ gravity, [ 13,14 ] $$f(G)$$ gravity, [ 15,16 ] $$f(T)$$ gravity, [ 17,18 ] $$f(Q)$$ gravity, [ 19,20 ] $$f(R,\, T)$$ gravity, [ 21,22 ] $$f(R,\, G)$$ gravity [ 23,24 ] etc. In the context of $$f(Q)$$ gravity, models of black hole, [ 25,26 ] wormholes, [ 27,28 ] cosmological models [ 29,30 ] were developed by several researchers.…”

“…To address this issue, many researchers modified the Einstein-Hilbert action to produce a new area of study known as modified gravity theories. The f (R) theory of gravity is the most well-known modified theory of gravity that replaces the Einstein-Hilbert action with a more general action by assuming that the gravitational action is given by any arbitrary function of the Ricci scalar R. The modified gravities that DOI: 10.1002/prop.202300074 attracted the researchers are f (R) gravity, [13,14] f (G) gravity, [15,16] f (T) gravity, [17,18] f (Q) gravity, [19,20] f (R, T) gravity, [21,22] f (R, G) gravity [23,24] etc. In the context of f (Q) gravity, models of black hole, [25,26] wormholes, [27,28] cosmological models [29,30] were developed by several researchers.…”