Near-Horizon Symmetries in Einstein-Maxwell theory

TL;DR

This paper derives near-horizon Einstein-Maxwell charges and fluxes for non-extremal black holes, clarifies the relation between Carrollian and Lorentz symmetries, and connects Einstein equations to flux-balance laws.

Contribution

It provides a detailed derivation of near-horizon charges in Einstein-Maxwell theory and links Carrollian internal boosts to Lorentz boosts, advancing understanding of black hole symmetries.

Findings

Derived explicit expressions for near-horizon charges and fluxes.

Established the equivalence of Carrollian and Lorentz internal boost symmetries.

Showed Einstein equations follow from flux-balance laws using Barnich-Troessaert bracket.

Abstract

This manuscript aims to provide a comprehensive derivation of the Einstein-Maxwell charges and fluxes in the near-horizon region of a four-dimensional non-extremal black hole, with vanishing cosmological constant. Specifically, we present a detailed derivation of the Noether charges within both the metric and first-order formulations, elucidating the relationship between the Carrollian internal boost charge and the Lorentz boost charge. It is well-established in the literature that Carrollian fluids exhibit an internal local boost symmetry; we demonstrate that this symmetry precisely corresponds to a Lorentz internal transformation. Finally, we prove that the near-horizon Einstein equations can be obtained from the flux-balance law by employing the generalized Barnich-Troessaert bracket.