Deflection angle of light for an observer and source at finite distance from a rotating wormhole

TL;DR

This paper calculates the light deflection angle near a rotating wormhole at finite distances using an improved optical metric method, comparing results with previous approaches and highlighting finite-distance corrections.

Contribution

It introduces a generalized optical metric approach to evaluate light deflection at finite distances in rotating wormhole spacetimes, extending previous asymptotic analyses.

Findings

The method yields results consistent with previous asymptotic approaches.

Finite-distance corrections to the deflection angle are derived.

The approach accounts for geodesic curvature contributions in the optical metric.

Abstract

By using a method improved with a generalized optical metric, the deflection of light for an observer and source at finite distance from a lens object in a stationary, axisymmetric and asymptotically flat spacetime has been recently discussed [Ono, Ishihara, Asada, Phys. Rev. D 96, 104037 (2017)]. By using this method, in the weak field approximation, we study the deflection angle of light for an observer and source at finite distance from a rotating Teo wormhole, especially by taking account of the contribution from the geodesic curvature of the light ray in a space associated with the generalized optical metric. Our result of the deflection angle of light is compared with a recent work on the same wormhole but limited within the asymptotic source and observer [Jusufi, Ovgun, Phys. Rev. D 97, 024042, (2018)], in which they employ another approach proposed by Werner with using the Nazim's osculating Riemannian construction method via the Randers-Finsler metric. We show that the two different methods give the same result in the asymptotic limit. We obtain also the corrections to the deflection angle due to the finite distance from the rotating wormhole.