Extrema of Mass, First Law of Black Hole Mechanics and Staticity Theorem in Einstein-Maxwell-axion-dilaton Gravity

TL;DR

This paper derives formulas for mass variation and the first law of black hole mechanics in Einstein-Maxwell-axion-dilaton gravity, establishing conditions for staticity of black hole solutions with bifurcate horizons.

Contribution

It generalizes the first law of black hole mechanics and staticity conditions to Einstein-Maxwell-axion-dilaton gravity using ADM formulation.

Findings

Derived formulas for mass and conserved quantities variation.

Established conditions for black hole staticity in this gravity theory.

Proved the solution is static under specific boundary conditions.

Abstract

Using the ADM formulation of the Einstein-Maxwell axion-dilaton gravity we derived the formulas for the variation of mass and other asymptotic conserved quantities in the theory under consideration. Generalizing this kind of reasoning to the initial dota for the manifold with an interior boundary we got the generalized first law of black hole mechanics. We consider an asymptotically flat solution to the Einstein-Maxwell axion-dilaton gravity describing a black hole with a Killing vector field timelike at infinity, the horizon of which comprises a bifurcate Killing horizon with a bifurcate surface. Supposing that the Killing vector field is asymptotically orthogonal to the static hypersurface with boundary S and compact interior, we find that the solution is static in the exterior world, when the timelike vector field is normal to the horizon and has vanishing electric and axion- electric fields on static slices.