Gravitational Lensing by Born-Infeld Naked Singularities

TL;DR

This paper investigates gravitational lensing effects caused by Born-Infeld naked singularities, revealing how nonlinearity allows photons to pass through singularities and affects the number of relativistic images and the appearance of shadows.

Contribution

It demonstrates that Born-Infeld naked singularities can have one or two photon spheres, enabling unique lensing phenomena and photon trajectories not seen in classical singularities.

Findings

Born-Infeld naked singularities have one or two photon spheres.

Nonlinearity allows photons to pass through the singularity.

No central shadow appears in images of celestial spheres.

Abstract

We examine the gravitational lensing phenomenon caused by photon spheres in the Born-Infeld naked singularity spacetime, where gravity is coupled with Born-Infeld electrodynamics. Specifically, our focus lies on relativistic images originating from a point-like light source generated by strong gravitational lensing near photon spheres, as well as images of a luminous celestial sphere. It shows that Born-Infeld naked singularities consistently exhibit one or two photon spheres, which project onto one or two critical curves on the image plane. Interestingly, we discover that the nonlinearity nature of the Born-Infeld electrodynamics enables photons to traverse the singularity, leading to the emergence of new relativistic images within the innermost critical curve. Furthermore, the presence of two photon spheres doubles the number of relativistic images compared to the scenario with only a single photon sphere. Additionally, the transparency inherent to Born-Infeld naked singularities results in the absence of a central shadow in the images of celestial spheres.