Black Hole and Wormhole Solutions in Einstein-Maxwell Scalar Theory

We classified and studied the charged black hole and wormhole solutions in the Einstein- Maxwell system in the presence of a massless, real scalar field. The possible existence of charged black holes in general scalar-tensor theories was studied in Bronnikov et al., 1999; black holes and wormholes exist for a negative kinetic term for the scalar field. Using a conformal transformation, the static, spherically symmetric possible structures in the minimal coupled system are described. Besides wormholes and naked singularities, only a restricted class of black hole exists, exhibiting a horizon with an infinite surface and a timelike central singularity. The black holes and wormholes defined in the Einstein frame have some specificities with respect to the non-minimal coupling original frame, which are discussed in the text.