# Strong gravitational lensing by wormholes

## TL;DR

This paper analyzes how strong gravitational lensing occurs around static wormholes, revealing unique features and potential observational signatures that distinguish wormholes from black holes.

## Contribution

It develops analytical methods for strong lensing by wormholes, highlighting novel phenomena like photon spheres on both sides of the throat and their implications.

## Key findings

- Photon and antiphoton spheres can exist on both sides of the wormhole.
- The wormhole throat can act as a photon sphere, affecting lensing.
- Lensing signatures are qualitatively different from black holes.

## Abstract

We study strong gravitational lensing by a class of static wormhole geometries. Analytical approaches to the same are developed, and the results differ substantially from strong lensing by black holes, first reported by Bozza. We consider two distinct situations, one in which the observer and the source are on the same side of the wormhole throat, and the other in which they are on opposite sides. Distinctive features in our study arise from the fact that photon and antiphoton spheres might be present on both sides of the wormhole throat, and that the throat might itself act as a photon sphere. We show that strong gravitational lensing thus opens up a rich variety of possibilities of relativistic image formation, some of which are novel, and are qualitatively distinct from black hole lensing. These can serve as clear indicators of exotic wormhole geometries.