Astrofisica

Gravitational lensing and black hole shadow

by Gennadi Bisnovatyi-Kogan (Space Research Institute - Russuan Academy of Science, Moscow)

Europe/Rome
Aula Rasetti (Dipartimento di Fisica - Ed. G. Marconi)

Aula Rasetti

Dipartimento di Fisica - Ed. G. Marconi

Description
An overview of the developments in problems of the effects of gravitational lensing is given, including plasma influence. Deflection of light in the presence of gravity and plasma is determined by a complex combination of various physical phenomena: gravity, dispersion, refraction. In particular, the gravitational deflection itself, in a homogeneous plasma without refraction, differs from the vacuum one and depends on the frequency of the photon. In an inhomogeneous plasma, chromatic refraction also takes place. We describe chromatic effects in strong lens systems including a shift of angular position of image and a change in magnification.