Shadow cast by a rotating black hole with anisotropic matter

TL;DR

This paper studies the shadow of a rotating black hole influenced by anisotropic matter, revealing how matter affects observable shadow features and analyzing the geodesic motion and brightness asymmetry.

Contribution

It introduces a model of a rotating black hole with anisotropic matter, derives the hidden symmetry, and examines how matter influences shadow observables and brightness asymmetry.

Findings

Anisotropic matter affects shadow size and shape.

Brightness asymmetry is linked to unstable photon orbits.

Shadow observables are quantitatively influenced by matter parameters.

Abstract

We obtain the shadow cast induced by the rotating black hole with an anisotropic matter. A Killing tensor representing the hidden symmetry is derived explicitly. The existence of separability structure implies a complete integrability of the geodesic motion. We analyze an effective potential around the unstable circular photon orbits to show that one side of the black hole is brighter than the other side. Further, it is shown that the inclusion of the anisotropic matter ($Kr^{2(1-w)}$) has an effect on the observables of the shadow cast. The shadow observables include approximate shadow radius $R_s$, distortion parameter $\delta_s$, area of the shadow $A_s$, and oblateness $D_{os}$.