Static and rotating electrically charged black holes in three-dimensional Brans-Dicke gravity theories - art. no. 064001

We obtain static and rotating electrically charged black holes of a Einstei n-Maxwell-dilaton theory of the Brans-Dicke type in 2+1 dimensions. The the ory is specified by three fields, the dilaton phi the graviton g(mu nu) and the electromagnetic field F-mu nu, and two parameters, the cosmological co nstant Lambda and the Brans-Dicke parameter omega. It contains eight differ ent cases, of which one distinguishes as special cases string theory, gener al relativity and a theory equivalent to four dimensional general relativit y with one Killing vector. We find the Arnowitt-Derer-Misner mass, angular momentum, electric charge and dilaton charge and compute the Hawking temper ature of the solutions. Causal structure and geodesic motion of null and ti melike particles in the black hole geometries are studied in detail.