Neutrinos from GRB 221009A: producing ALPs and explaining LHAASO anomalous $\gamma$ event

TL;DR

This paper proposes a novel mechanism where high-energy neutrinos from GRB 221009A convert into axion-like particles, which then transform into gamma rays, providing an explanation for the observed 18 TeV gamma-ray event while satisfying existing observational constraints.

Contribution

It introduces a new neutrino-ALP-photon conversion model to explain high-energy gamma-ray observations from GRBs, integrating constraints and potential future tests.

Findings

Identifies parameter space consistent with current bounds that explains the 18 TeV gamma-ray.

Predicts a correlation between neutrino and gamma-ray fluxes for future observational tests.

Shows how the model can be embedded in electroweak-invariant frameworks avoiding cosmological bounds.

Abstract

We propose a novel explanation for the 18 TeV gamma ray from GRB 221009A observed by LHAASO. High-energy neutrinos are converted into axion-like particles (ALPs) via their interaction with the cosmic neutrino background. Subsequently, ALPs are converted into high-energy photons in the magnetic field of our galaxy. We compute the fluxes of neutrinos, ALPs, and photons reaching Earth. IceCube's constraints on the neutrino flux from GRB 221009A translate into a severe upper bound on the photon flux. We find a range of parameters where all existing bounds are satisfied and the 18 TeV LHAASO photon can be explained. In the future, the specific correlation between the photon and neutrino flux reaching Earth from powerful neutrino sources with energies larger than 10 TeV such as GRBs or AGNs, can be used as a tool to differentiate our explanation from the alternatives suggested in the literature. We discuss how the interactions of our scenario can be embedded within electroweak gauge-invariant models, avoiding various cosmological and terrestrial bounds. We comment on the possibility of explaining the 251 TeV photon observed by the Carpet-2 detector, taking into account the bounds from the observation of high-energy neutrinos from TXS 0506+056.