Contributed Talk - Splinter Compact

Thursday, 14 September 2023, 16:45   (H 2036)

Gravitational lensing by a Schwarzschild black hole surrounded by a plasma

Volker Perlick
ZARM, University of Bremen

A stationary, axisymmetric, non-magnetised and pressureless plasma is considered around a Schwarzschild black hole. A Hamiltonian formalism is used for determining the light rays. The necessary and sufficient condition on the plasma density is given for the equation of motion to be completely integrable; if this condition is not satisfied, the motion is chaotic. If this condition holds, the shadow of the black hole can be analytically calculated. Also, the condition for circular light rays is given. In a plasma, circular light rays may exist off the equatorial plane. The influence of the plasma on the deflection angle is discussed as well. - The talk is partly based on joint work with Oleg Yu. Tsupko.