Mass formulae and staticity condition for dark matter charged black holes

TL;DR

This paper derives mass formulae and staticity conditions for dark matter charged black holes within Einstein-Maxwell dark matter gravity, revealing that static solutions with certain horizon properties must have vanishing magnetic fields.

Contribution

It introduces generalized mass and first law formulas for black holes in a dark matter coupled Einstein-Maxwell framework, highlighting conditions for staticity and magnetic field vanishing.

Findings

Static black holes with bifurcate horizons are non-rotating and have zero magnetic fields.

The study extends black hole thermodynamics to include dark matter sector effects.

Mass and energy variations are derived using ADM formalism in this modified gravity context.

Abstract

The Arnowitt-Deser-Misner formalism is used to derive variations of mass, angular momentum and canonical energy for Einstein-Maxwell {\it dark matter} gravity in which the auxiliary gauge field coupled via kinetic mixing term to the ordinary Maxwell one, which mimics properties of {\it hidden sector}. Inspection of the initial data for the manifold with an interior boundary, having topology of $S^2$, enables us to find the generalised first law of black hole thermodynamics in the aforementioned theory. It has been revealed that the stationary black hole solution being subject to the condition of encompassing a bifurcate Killing horizon with a bifurcation sphere, which is non-rotating, must be static and has vanishing {\it magnetic} Maxwell and {\it dark matter} sector fields, on static slices of the spacetime under consideration.