Noether Currents of Charged Spherical Black Holes

Abstract

We calculate the Noether currents and charges for Einstein-Maxwell theory using a version of the Wald approach. In spherical symmetry, the choice of time can be taken as the Kodama vector. For the static case, the resulting combined Einstein-Maxwell charge is just the mass of the black hole. Using either a classically defined entropy or the Iyer-Wald selection rules, the entropy is found to be just a quarter of the area of the trapping horizon. We propose identifying the combined Noether charge as an energy associated with the Kodama time. For the extremal black hole case, we discuss the problem of Wald's rescaling of the surface gravity to define the entropy.

4 pages

References in corpus (3)

• Black Hole Entropy from Conformal Field Theory in Any Dimension
• Dynamic black-hole entropy
• Boundary Terms and Noether Current of Sphereical Black Holes

Cited by in corpus (4)

• Classical and Quantum Thermodynamics of horizons in spherically symmetric spacetimes
• Dynamical Structure of Irregular Constrained Systems
• Thermality and Heat Content of horizons from infinitesimal coordinate transformations
• Nöther Currents, Black Hole Entropy Universality and CFT Duality in Conformal Weyl Gravity