Optical phenomena in brany Kerr spacetimes

TL;DR

This paper investigates how the tidal charge parameter in braneworld models affects optical phenomena around rotating black holes, revealing that negative tidal values enhance relativistic effects and alter observable features.

Contribution

It provides a detailed analysis of optical phenomena in brany Kerr spacetimes, including photon escape cones, black hole silhouettes, and time delays, with a focus on the impact of tidal parameters.

Findings

Negative tidal parameters strengthen relativistic effects.

Tidal parameters influence the shape of black hole silhouettes.

Optical phenomena are classified based on black hole parameters.

Abstract

We study the influence of the tidal charge parameter of the braneworld models onto some optical phenomena in rotating black hole spacetimes. The escape photon cones are determined for special families of locally non-rotating, circular geodetical and radially free falling observers. The silhouette of a rotating black hole, the shape of an equatorial thin accretion disk and time delay effect for direct and indirect images of a radiation hot spot orbiting the black hole are given and classified in terms of the black hole rotational and tidal parameters. It is shown that rising of negatively-valued tidal parameter, with rotational parameter fixed, generally strenghtens the relativistic effects and suppresses the rotation induced asymmetries in the optical phenomena.