GRB 221009A Gamma Rays from the Radiative Decay of Heavy Neutrinos?

We consider a mechanism that causes a decrease in the attenuation of high energy gamma-ray flux from gamma ray burst GRB 221009A. The mechanism is based on the existence of a heavy mN & SIM; (0.1 - 1) MeV mostly sterile neutrino N which mixes with active neutrinos. N's are produced in the gamma-ray burst (GRB) in & pi; and K decays via mixing with & nu;& mu;. They undergo the radiative decay N -& nu;& gamma; on the way to Earth. The usual exponential attenuation of gamma rays is lifted to an attenuation inverse in the optical depth. Various restrictions on this scenario are discussed. We find that the high energy & gamma; events at 18 TeV can be explained if (i) the GRB active neutrino fluence is close to the observed limit, (ii) the branching ratio of N -& nu;& gamma; is at least of the order 10%.

Automated summary

This paragraph discusses a mechanism that leads to a decrease in the attenuation of high energy gamma-ray flux from gamma-ray burst GRB 221009A. The mechanism is based on the existence of mostly sterile neutrino N with a mass of (0.1 - 1) MeV, which mixes with active neutrinos. The N particles are produced in the gamma-ray burst through π and K decays, and they undergo radiative decay N - νγ on their way to Earth. Various restrictions on this scenario are examined, and it is found that the high energy γ events at 18 TeV can be explained under certain conditions.