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

Area of Science:

• Astrophysics
• Particle Physics

Background:

• High-energy gamma-ray flux from Gamma Ray Burst (GRB) 221009A shows unexpectedly low attenuation.
• Standard models of gamma-ray propagation do not fully account for this observation.

Purpose of the Study:

• To propose and investigate a mechanism involving sterile neutrinos that reduces gamma-ray attenuation.
• To explain the observed high-energy gamma-ray events from GRB 221009A.

Main Methods:

• Consideration of a heavy, mostly sterile neutrino (N) with a mass of approximately 0.1-1 MeV.
• Modeling the production of sterile neutrinos in GRBs via mixing with muon neutrinos (νμ) during pion and kaon decays.
• Analysis of radiative decay of sterile neutrinos (N→νγ) during their propagation to Earth.

Main Results:

• The proposed mechanism replaces exponential attenuation with inverse attenuation in optical depth.
• High-energy gamma-ray events at 18 TeV can be explained under specific conditions.
• Conditions include GRB active neutrino fluence near the observed limit and a branching ratio of N→νγ of at least 10%.

Conclusions:

• The existence and radiative decay of heavy sterile neutrinos provide a viable explanation for the observed low attenuation of high-energy gamma rays from GRB 221009A.
• This scenario offers a new perspective on gamma-ray burst physics and neutrino properties.