# Retrolensing by a wormhole at deflection angles $\pi$ and $3\pi$

## TL;DR

This paper investigates the unique retrolensing light curves caused by an Ellis wormhole with large deflection angles, demonstrating how their features can distinguish wormholes from black holes through observable light curve peaks.

## Contribution

It introduces the analysis of retrolensing light curves with deflection angles π and 3π by an Ellis wormhole, highlighting how their distinct peaks can identify wormholes.

## Key findings

- Light curves with two peaks can be used to identify Ellis wormholes.
- Separable peaks in light curves provide information on the lens object.
- Distinct features differentiate wormhole retrolensing from black hole signals.

## Abstract

The deflection angle of a light ray can be arbitrarily large near a light sphere. The time-symmetrical shape of light curves of a pair of light rays reflected by a light sphere of a lens object does not depend on the details of the lens object. We consider retrolensing light curves of sunlight with deflection angles $\pi$ and $3\pi$ by an Ellis wormhole, which is the simplest Morris-Thorne wormhole. If an Ellis wormhole with a throat parameter $a=10^{11}$ km is $100$ pc away from an observer and if the Ellis wormhole, the observer, and the sun are aligned perfectly in this order, the apparent magnitudes of a pair of light rays with deflection angles $\pi$ and $3\pi$ become $11$ and $18$, respectively. The two pairs of light rays make a superposed light curve with two separable peaks and they break down time symmetry of a retrolensing light curve. The observation of the two separated peaks of the light curves gives us information on the details of the lens object. If the observer can also separate the pair of the images with the deflection angle $\pi$ into a double image, he or she can say whether the retrolensing is caused by an Ellis wormhole or a Schwarzschild black hole.