Resonant oscillations of GeV - TeV neutrinos in internal shocks from gamma-ray burst jets inside the stars

TL;DR

This paper investigates how thermal and magnetic plasma in internal shocks of gamma-ray burst jets inside stars affects neutrino oscillations, concluding that flavor ratios on Earth remain close to standard expectations despite resonant oscillations.

Contribution

It introduces a detailed analysis of neutrino oscillations considering plasma effects in GRB internal shocks, highlighting the minimal impact on observable flavor ratios.

Findings

Neutrino oscillations can occur resonantly in GRB internal shocks.

The flavor ratio of neutrinos arriving at Earth remains close to 1:1:1.

Plasma effects have limited influence on the observable neutrino flavor composition.

Abstract

High-energy neutrinos generated in collimated jets inside the progenitors of gamma-ray bursts (GRBs) have been related with the events detected by IceCube. These neutrinos, produced by hadronic interactions of Fermi-accelerated protons with thermal photons and hadrons in internal shocks, are the only signature when jet has not broken out or failed. Taking into account that the photon field is thermalized at keV energies and the standard assumption that the magnetic field maintains a steady value throughout the shock region (with a width of $10^{10} - 10^{11}$ cm in the observed frame), we study the effect of thermal and magnetized plasma generated in internal shocks on the neutrino oscillations. We calculate the neutrino effective potential generated by this plasma, the effects of the envelope of the star, and the vacuum on the path to Earth. By considering these three effects, the two (solar, atmospheric and accelerator parameters) and three neutrino mixing, we show that although GeV - TeV neutrinos can oscillate resonantly from one flavor to another, a nonsignificant deviation of the standard flavor ratio (1:1:1) could be expected on Earth.