Wave Effect in Gravitational Lensing by the Ellis Wormhole

TL;DR

This paper explores how wave effects in gravitational lensing can distinguish Ellis wormholes from point mass lenses, proposing a method to detect such wormholes via spectral modulation in low-frequency astronomical observations.

Contribution

It introduces a wave effect-based approach to differentiate Ellis wormholes from point mass lenses, resolving degeneracy in geometrical optics approximation.

Findings

Wave effects become significant at low frequencies, enabling wormhole detection.

Estimated upper bound for Ellis wormhole density is $n\lesssim 10^{-9}\{AU}^{-3}$.

Method can utilize existing femto-lensing data for constraints.

Abstract

We propose the use of modulated spectra of astronomical sources due to gravitational lensing to probe Ellis wormholes. The modulation factor due to gravitational lensing by the Ellis wormhole is calculated. Within the geometrical optics approximation, the normal point mass lens and the Ellis wormhole are indistinguishable unless we know the source's unlensed luminosity. This degeneracy is resolved with the significant wave effect in the low frequency domain if we take the deviation from the geometrical optics into account. We can roughly estimate the upper bound for the number density of Ellis wormholes as $n\lesssim 10^{-9}\{AU}^{-3}$ with throat radius $a\sim1\cm$ from the existing femto-lensing analysis for compact objects.