Electromagnetic and observational signatures of the Kerr-Taub-NUT spacetime

While it is expected that Sgr A* is described by the Kerr solution, general relativity has yet to be tested rigorously in the strong-field regime. It is eminently possible that alternative spacetimes, and even alternative theories of gravity may describe the black hole candidate in our Galactic centre. To this end, we investigate the possibility of distinguishing a black hole in the Kerr-Taub-NUT (KTN) spacetime from the standard Kerr solution. Coupling ray-tracing calculations with a fully covariant general-relativistic (GR) radiative transport formalism we calculate and compare the observed electromagnetic emissions and images from the vicinity of both KTN and Kerr spacetimes.