Hamburg 2016 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 11: Classical General Relativity II

GR 11.2: Invited Talk

Thursday, March 3, 2016, 14:25–15:05, VMP6 HS A

Influence of a plasma on gravitational lensing by compact objects — •Volker Perlick — ZARM, University of Bremen, Germany

I discuss light bending by compact objects (black holes, wormholes, ultracompact stars, etc.) that are surrounded by a plasma. The plasma is assumed to be pressureless (``cold''), non-magnetised and optically thin. After deriving the general formula for the bending angle in a plasma under the assumption of spherical symmetry and staticity, I discuss in some detail the angular diameter of the shadow of a compact object in a plasma, again under the same symmetry assumptions. The Schwarzschild spacetime and the Ellis wormhole are treated as particular examples. In the last part, I consider a plasma on the Kerr spacetime. The perspectives of actually observing the discussed effects with supermassive black holes will be addressed as well. - The talk is largely based on joint work with Oleg Tsupko and Gennady Bisnovatyi-Kogan (Space Research Institute, Russian Academy of Science, Moscow).