Cosmological Constant Effect on Charged and Rotating Black Hole Shadows

Abstract

Motivated by recent astrophysical observations, we investigate the shadow behaviors of four dimensional charged rotating black holes with a cosmological constant. This study is made in terms of a reduced moduli space parameterized by the charge and the rotation parameters. For fixed observers, we analyse in some details the shadow behaviors and the corresponding naked singularities of Kerr-Newman and Kerr-Sen four-dimensional black holes in Anti de Sitter backgrounds. Then, a comparative discussion is provided by computing the geometrical observables and the energy emission rate.