Charged, rotating black holes in Einstein-Maxwell-dilaton theory

Abstract The asymptotically flat, electrically charged, rotating black holes (BHs) in Einstein-Maxwell-dilaton (EMd) theory are known in closed form for only two particular values of the dilaton coupling constant γ : the Einstein-Maxwell coupling ( γ = 0), corresponding to the Kerr-Newman (KN) solution, and the Kaluza-Klein coupling ( γ = √(3)). Rotating solutions with arbitrary γ are known only in the slow-rotation or weakly charged limits. In this work, we numerically construct such EMd BHs with arbitrary γ . We present an overview of the parameter space of the solutions for illustrative values of γ together with a study of their basic properties. The solutions are in general KN-like; there are however, new features. The data suggest that the spinning solutions with 0< γ <√(3) possess a zero temperature limit, which, albeit regular in terms of curvature invariants, exhibits a pp-singularity. A different limiting behaviour is found for γ >√(3), in which case, moreover, we have found hints of BH non-uniqueness for the same global charges.