Strong deflection lensing by charged black holes in scalar-tensor gravity

Abstract

We examine a class of charged black holes in scalar-tensor gravity as gravitational lenses. We find the deflection angle in the strong deflection limit, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to the Reissner-Norström spacetime and we analyze the observational aspects in the case of the Galactic supermassive black hole.