On the shadow of rotating traversable wormholes

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.