A novel gravitational lensing feature by wormholes

Understand

Horizonless compact objects with light rings (or photon spheres) are becoming increasingly popular in recent years for several reasons.

• In this paper, we show that a horizonless object such as a wormhole of Morris-Thorne type can have two photon spheres.
• In particular, we show that, in addition to the one present outside a wormhole throat, the throat can itself act as an effective photon sphere.
• Such wormholes exhibit two sets of relativistic Einstein ring systems formed due to strong gravitational lensing.