Black holes and wormholes subject to conformal mappings

Solutions of the field equations of theories of gravity which admit distinct conformal frame representations can look very different in these frames. We show that Brans class IV solutions describe wormholes in the Jordan frame (in a certain parameter range) but correspond to horizonless geometries in the Einstein frame. The reasons for such a change of behavior under conformal mappings are elucidated in general, using Brans IV solutions as an example. We end with a brief discussion of the Schwarzschild case and a conformally related metric as a further example of some of the peculiarities of the behavior of horizons under conformal transformations.