Gamma Ray Burst GRB 221009A: two distinct hints at once at new physics

TL;DR

This paper discusses two potential new physics explanations—axion-like particles and Lorentz invariance violation—for the observation of extremely high-energy gamma-ray photons from GRB 221009A, challenging conventional physics expectations.

Contribution

It demonstrates that Lorentz invariance violation could explain the detection of 251 TeV photons, providing an alternative to axion-like particles for explaining such high-energy observations.

Findings

Detection of 251 TeV photon is robust.

Conventional physics cannot explain such high-energy photons due to EBL absorption.

Lorentz invariance violation offers a plausible explanation.

Abstract

The brightest ever observed gamma ray burst GRB 221009A at redshift $z = 0.151$ was detected on October 9, 2022. Its highest energy photons have been recorded by the LHAASO collaboration up to above $12 \, \rm TeV$, and one of the at ${\cal E} = 251 \, \rm TeV$ by the Carpet-2 collaboration. Very recently, the Carpet-3 collaboration has completed the data analysis, showing that the evidence of the $251 \, {\rm TeV}$ photon is quite robust. Still, according to conventional physics photons with ${\cal E} \gtrsim 10 \, \rm TeV$ cannot be observed owing to the absorption by the extragalactic background light (EBL). Previously it has been demonstrated that an axion-like particle (ALP) with allowed parameters ensures the observability of the LHAASO photons. Here we show that the Lorentz invariance violation allows the ${\cal E} = 251 \, {\rm TeV}$ (now around 300 TeV) Carpet photon to be detected.