On the shadow of rotating traversable wormholes

TL;DR

This paper investigates how the throat of rotating traversable wormholes influences their shadow shapes, revealing unique features like cuspy edges caused by unstable spherical orbits, thus enhancing understanding of wormhole imaging.

Contribution

It analyzes the role of the wormhole throat in shadow formation and uncovers mechanisms behind cusp features in shadow images for specific wormhole solutions.

Findings

Throat acts as a potential barrier affecting shadow shape

Some shadows exhibit cuspy edges due to unstable orbits

Mechanisms for cusp formation are explicitly identified

Abstract

We revisit the shadow of rotating traversable wormholes discussing the role of the wormhole throat in the shadow formation. For certain classes of wormholes the throat serves as a potential barrier for light rays with particular impact parameters, thus modifying the shadow shape. We consider a couple of wormhole solutions and examine the structure of their shadow images, and the intrinsic mechanisms for their formation. Some of the shadows possess cuspy edges, which arise due to the interplay of two distinct families of unstable spherical orbits. These solutions provide examples, in which the explicit mechanism for cusp formation can be uncovered.