# An experimental test of gravity at high energy

## TL;DR

This paper explores testing gravity at high energy using gravitational lensing of high-energy photons, analyzing time delays within a LIV framework, and discusses potential constraints from future observations, despite current bounds being less competitive.

## Contribution

It introduces a method to test high-energy gravity through photon time delays in gravitational lensing, applicable to LIV and other models, emphasizing model-independent bounds.

## Key findings

- Time delay analysis in LIV framework for high-energy photons.
- Potential constraints on high-energy gravity from future lensing observations.
- Current bounds are less competitive but free from emission process assumptions.

## Abstract

Gravitational lensing of very high energy photons has recently been observed in the JVAS B0218+357 strong lensing system. This observation opens the possibility of performing a test of gravity at high energy by comparing the difference in propagation time of high energy photons over different travel paths. The time delay is computed in the framework of a LIV (Lorentz Invariance Violation) extension of the equations of motion of photons in the field of a massive object. However, the method obtained can be transposed to other models of gravity at high energy. The potential for constraining high energy gravity with future observations of JVAS B0218+357 is discussed. The bounds on the LIV energy scale will not be competitive with other astrophysical bounds such as those coming from AGN and GRB flares. However, these bounds are free of any assumption on the emission process.