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 $\phi ,$ the graviton $g_{\mu \nu }$ and the electromagnetic field $F^{\mu \nu },$ and two parameters, the cosmological constant $\Lambda$ and the Brans-Dicke parameter $\omega .$ 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 Arnowitt-Derer-Misner 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.

• Received 30 April 2001

DOI:https://doi.org/10.1103/PhysRevD.64.064001