Black Hole Shadows As New Tests of General Relativity

Despite the fact that several alternative theories of gravity have been proposed, (many of them have been suggested in the recent years) the general relativity (GR), created more than 100 years ago, is still the best theory of gravity. Due to the great technological progress of observational and experimental facilities currently there are opportunities to test gravity theories in a strong gravitational field limit. In 2005 we proposed to use a shadow near the black hole at the Galactic Center (GC) as a GR test. We predicted also that the shadow can be reconstructed from observations of bright structures near the black hole. Our prediction concerning the shadow near the black hole at the Galactic Center has been confirmed, since in 2022 the Event Horizon Telescope (EHT) collaboration reconstructed the shadow from EHT observations done in April 2017.