Rotating ( 2+1 )-dimensional black holes in Einstein-Maxwell-dilaton theory

Abstract

We consider Einstein-Maxwell-dilaton theory in ($2+1$) dimensions where the coupling between the scalar field and the Maxwell invariant is the dilatonic coupling $f(\ensuremath{\phi})=\mathrm{exp}(\ensuremath{-}2\ensuremath{\alpha}\ensuremath{\phi})$, and we obtain novel, exact, rotating black hole solutions. The dilatonic parameter $\ensuremath{\alpha}$ impacts the metric function, affecting the rotating properties of the black hole, its mass, and also its thermodynamics. Calculating the entropy we find that it is always positive, and the dilatonic black holes may have higher entropy than the BTZ black hole. Depending on the parameters, the dilatonic BTZ-like black hole may be thermodynamically preferred over the BTZ black hole which is recovered when $\ensuremath{\alpha}=0$.