Dyonic RN-like and Taub-NUT-like black holes in Einstein-bumblebee gravity
Shoulong Li, Liang Liang, Liang Ma
TL;DR
This work constructs exact four-dimensional dyonic Reissner–Nordström–like black holes with topological horizons in Einstein-bumblebee gravity, a simple vector-tensor theory that implements spontaneous Lorentz symmetry breaking. By solving the coupled Einstein–bumblebee–Maxwell equations, the authors obtain an exact dyonic solution with metric functions h and f related by ℓ = b^2 γ, and electric/magnetic charges q and p, while imposing specific nonminimal couplings γ1, γ2 to ensure consistency (γ1 = γ/[4(2+3ℓ)], γ2 = -2γ(1+ℓ)/[(2+ℓ)(2+3ℓ)]). They then establish a consistent first law of black hole thermodynamics using the Wald formalism, calculating mass and entropy in a way that resolves previous ambiguities in these Lorentz-violating setups. The paper also extends to Taub–NUT–like dyonic solutions, and generalizes the RN-like construction to higher even dimensions, providing explicit expressions for thermodynamic quantities and Smarr relations. Together, these results illuminate the impact of spontaneous Lorentz symmetry breaking on black hole physics and offer a robust framework for exploring observational signatures in extended gravity models.
Abstract
Einstein-bumblebee gravity is one of the simplest vector-tensor theories that realizes spontaneous Lorentz symmetry breaking. In this work, we first construct an exact dyonic Reissner-Nordström-like black hole solution in four dimensions, carrying both electric and magnetic charges and admitting general topological horizons. We then study its thermodynamic properties, and employ the Wald formalism to compute the conserved mass and entropy, thereby establishing the first law of black hole thermodynamics. Furthermore, we generalize these results to Taub-Newman-Unti-Tamburino case and higher dimensions case.
