Black holes, dark wormholes, and solitons in f (T) gravities

By choosing an appropriate vielbein basis, we obtain a class of spherically-symmetric solutions in f(T) gravities. The solutions are asymptotic to Minkowski spacetimes with leading falloffs the same as those of the Schwarzschild black hole. In general, these solutions have branch-cut singularities in the middle. For appropriately chosen f(T) functions, extremal black holes can also emerge. Furthermore, we obtain wormhole configurations whose spatial section is analogous to an Ellis wormhole, but -g(tt) runs from 0 to 1 as the proper radial coordinate runs from -infinity to +infinity. Thus a signal sent from -infinity to +infinity through the wormhole will be infinitely red-shifted. We call such a spacetime configuration a dark wormhole. By introducing a bare cosmological constant Lambda(0), we construct smooth solitons that are asymptotic to local AdS with an effective Lambda(eff). In the middle of bulk, the soliton metric behaves like the AdS of bare Lambda(0) in global coordinates. We also embed AdS planar and Lifshitz black holes in f(T) gravities. Finally we couple the Maxwell field to the f(T) theories and construct electrically-charged solutions.