Shadows as a tool to evaluate black hole parameters and a dimension of spacetime

• Published in: New astronomy reviews 2012-02, Vol.56 (2-3), p.64-73
• Main Authors: Zakharov, Alexander F., Paolis, Francesco De, Ingrosso, Gabriele, Nucita, Achille A.
• Format: Article
• Language: English
• ISSN: 1387-6473; 1872-9630
• DOI: 10.1016/j.newar.2011.09.002

Shadow formation around supermassive black holes were simulated. Due to enormous progress in observational facilities and techniques of data analysis researchers approach to opportunity to measure shapes and sizes of the shadows at least for the closest supermassive black hole at the Galactic Center. Measurements of the shadow sizes around the black holes can help to evaluate parameters of black hole metric. Theories with extra dimensions (Randall–Sundrum II braneworld approach, for instance) admit astrophysical objects (supermassive black holes, in particular) which are rather different from standard ones. Different tests were proposed to discover signatures of extra dimensions in supermassive black holes since the gravitational field may be different from the standard one in the general relativity (GR) approach. In particular, gravitational lensing features are different for alternative gravity theories with extra dimensions and general relativity. Therefore, there is an opportunity to find signatures of extra dimensions in supermassive black holes. We show how measurements of the shadow sizes can put constraints on parameters of black hole in spacetime with extra dimensions.