Shadow of axisymmetric, stationary and asymptotically flat black holes in the presence of plasma

Understand

We study the shadow produced by a class of rotating black holes surrounded by plasma.

• The metric for these black holes arises by applying the Newman-Janis algorithm to a family of spherically symmetric spacetimes, which includes several well known geometries as special cases.
• We derive a general expression for the shape of the shadow in the case that the plasma frequency leads to a separable Hamilton-Jacobi equation for light.
• We present two examples in which we obtain the shadow contours and the observables resulting from them.