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GL3 - Gravitational lensing: theory and numerical modeling

Speaker

Perlick, Volker

Coauthors

Tsupko, Oleg Yu.; Bisnovatyi-Kogan, Gennady S.

Talk Title

Influence of a Plasma on the Shadow of a Spherically Symmetric Black Hole

Abstract

The shadow of a black hole is the region on the observer's sky that is left dark if light sources are distributed anywhere but not between the black hole and the observer. Here we present analytical formulas for the size of the shadow for the case of light propagation in a non-magnetised cold plasma. We do the general calculations under the assumptions that both the spacetime geometry and the plasma density are spherically symmetric and static, then we specialise to the Schwarzschild geometry and a density profile that corresponds to spherically symmetric accretion of a dust. We estimate the chances of actually observing effects of a plasma for the black-hole candidate at the centre of our galaxy.

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