Researchers at the Large High Altitude Air Shower Observatory (LHAASO) in China have tested Lorentz invariance by analyzing measurements of a gamma-ray burst (GRB). The team studied GRB 221009A, the brightest event ever observed and one of the closest, at a distance of about 2.4 billion light years.
The analysis focused on how the energy spectrum of the GRB changed over time, constraining two main terms that describe light’s potential frequency dispersion. For the linear term, they obtained similar results to previous studies using GRBs. For the quadratic term, they established a five- to sevenfold greater energy threshold at which quantum gravity could emerge.
The study demonstrates that future observations of the initial stages of a GRB could offer even more sensitive Lorentz-violation tests. The findings raise the energy threshold at which quantum gravity effects might become evident, providing new constraints on theories of quantum gravity.
Source: https://physics.aps.org/articles/v17/s99