Gravitational lensing by two photon spheres in a black-bounce spacetime in strong deflection limits

TL;DR

This paper studies gravitational lensing effects caused by two photon spheres in a black-bounce spacetime, revealing complex image formations including multiple images due to light reflection near the antiphoton sphere.

Contribution

It introduces the analysis of lensing by dual photon spheres in black-bounce spacetimes, highlighting the role of the antiphoton sphere in image formation in strong deflection limits.

Findings

Multiple images form outside and inside photon spheres.

Infinite images result from light reflection near the antiphoton sphere.

Distinct lensing signatures could indicate the presence of a black-bounce spacetime.

Abstract

We investigate gravitational lensing by a primary photon sphere which is a sphere filled with unstable circular light orbits, and by a secondary photon sphere on a wormhole throat in a black-bounce spacetime which is suggested in [F. S. N. Lobo, M. E. Rodrigues, M. V. d. S. Silva, A. Simpson, and M. Visser, Phys. Rev. D 103, 084052 (2021)] in strong deflection limits. There is an antiphoton sphere between the primary photon sphere and the secondary photon sphere. If a light source and an observer are on the same side of the wormhole throat, in addition to an infinite number of images slightly outside of both the primary and secondary photon spheres, an infinite number of images formed by light rays reflected by the potential barrier near the antiphoton sphere, slightly inside the primary photon sphere, might be observed.