Lorentz violation from cosmological objects with very high energy photon emissions

Understand

Lorentz violation (LV) is predicted by some quantum gravity theories, where photon dispersion relation is modified, and the speed of light becomes energy-dependent.

• Consequently, it results in a tiny time delay between high energy photons and low energy ones.
• Very high energy (VHE) photon emissions from cosmological distance can amplify these tiny LV effects into observable quantities.
• Here we analyze four VHE $\gamma$-ray bursts (GRBs) from Fermi observations, and briefly review the constraints from three TeV flares of active galactic nuclei (AGNs) as well.