Contribution to the extragalactic neutrino background from dense environment of GRB jets

TL;DR

This paper models how hadrons accelerated in long gamma-ray burst jets interact with dense surrounding material, producing neutrino afterglows that contribute to the extragalactic neutrino background detected by IceCube.

Contribution

It introduces a novel scenario where neutrino afterglows from dense environments of GRB jets significantly contribute to the extragalactic neutrino background.

Findings

Neutrino spectra from hadron interactions in dense stellar environments are calculated.

Neutrino afterglows can occur on long timescales, making association with specific GRBs difficult.

Estimated contribution of these neutrinos to the IceCube background is significant.

Abstract

Long gamma-ray bursts (GRBs) are at present well confirmed sites of acceleration of particles to relativistic energies due to observations of gamma-ray emission in the GeV-TeV energy range. We consider a scenario in which the mechanism accelerating electrons is also responsible for acceleration of hadrons in the GRB jets to multi-PeV energies. Since progenitors of long GRBs are massive stars still immersed in dense stellar clusters, these hadrons can efficiently interact with the matter after escaping from the jet. We calculate the spectra of neutrinos from the interaction of those hadrons with the matter of a huge cloud surrounding GRB. Those neutrinos form an afterglow on a time scale determined by their diffusion time scale in the cloud. Due to this long delay, their identification with any specific GRB is not possible. We estimate contribution of neutrinos from such afterglows to the extragalactic neutrino background recently reported by the IceCube Observatory.