Static and rotating electrically charged black holes in three-dimensional Brans-Dicke gravity theories

TL;DR

This paper derives and analyzes static and rotating electrically charged black hole solutions in a (2+1)-dimensional Brans-Dicke type Einstein-Maxwell-Dilaton theory, exploring their physical properties and causal structures.

Contribution

It presents new exact black hole solutions in a generalized Brans-Dicke framework, covering multiple special cases including string theory and general relativity.

Findings

Computed ADM mass, angular momentum, electric and dilaton charges.

Analyzed Hawking temperature and causal structure.

Studied geodesic motion in black hole geometries.

Abstract

We obtain static and rotating electrically charged black holes of a Einstein-Maxwell-Dilaton theory of the Brans-Dicke type in (2+1)-dimensions. The theory is specified by three fields, the dilaton, the graviton and the electromagnetic field, and two parameters, the cosmological constant and the Brans-Dicke parameter. It contains eight different cases, of which one distinguishes as special cases, string theory, general relativity and a theory equivalent to four dimensional general relativity with one Killing vector. We find the ADM mass, angular momentum, electric charge and dilaton charge and compute the Hawking temperature of the solutions. Causal structure and geodesic motion of null and timelike particles in the black hole geometries are studied in detail.