Eur. Phys. J. C (2015) 75: 315
https://doi.org/10.1140/epjc/s10052-015-3539-x

Regular Article - Experimental Physics

Shadows of CPR black holes and tests of the Kerr metric

Department of Physics, Center for Field Theory and Particle Physics, Fudan University, Shanghai, 200433, China

^* e-mail: bambi@fudan.edu.cn

Received: 8 June 2015
Accepted: 24 June 2015
Published online: 8 July 2015

Abstract

We study the shadow of the Cardoso–Pani–Rico black hole for different values of the black hole spin , the deformation parameters and , and the viewing angle i. We find that the main impact of the deformation parameter is the change of the size of the shadow, while the deformation parameter affects the shape of its boundary. In general, it is impossible to test the Kerr metric, because the shadow of a Kerr black hole can be reproduced quite well by a black hole with non-vanishing or . Deviations from the Kerr geometry could be constrained in the presence of high quality data and in the favorable case of a black hole with high values of and i. However, the shadows of some black holes with non-vanishing present peculiar features and the possible detection of these shadows could unambiguously distinguish these objects from the standard Kerr black holes of general relativity.