Light trajectory and shadow shape in the rotating naked singularity

TL;DR

This paper explores how light trajectories and shadows differ in rotating naked singularity spacetimes compared to Kerr black holes, revealing unique shadow shapes and photon sphere properties.

Contribution

It introduces a new analysis of light paths and shadow shapes in rotating naked singularity spacetimes derived without complexification, contrasting them with Kerr black holes.

Findings

Naked singularity projects an arc-shaped shadow.

Photon sphere exists only for retrograde orbits in RNS.

Shadow shape differs significantly from Kerr black holes.

Abstract

In this paper, we investigate the light trajectories and shadow properties in the rotating version of null naked singularity (NNS) spacetime which is derived using the Newman- Janis algorithm without complexification method. We discuss some of the geometrical properties and causal structure of Rotating Naked Singularity (RNS) spacetime. The gravitational lensing in a rotating naked singularity is analyzed, and the results are compared to those of a Kerr black hole. In the case of a Kerr black hole, the photon sphere exists for both prograde and retrograde photon orbits, whereas for RNS, the photon sphere exists only for retrograde photon orbits. As a result, the naked singularity projects an arc-shaped shadow that differs from the contour-shaped shadow cast by a Kerr black hole.