High-energy neutrinos from cosmic ray interactions in the Local Bubble

TL;DR

This paper proposes that interactions of PeV cosmic rays in the Local Bubble wall could explain observed high-energy neutrino and gamma-ray excesses, linking Galactic sources to these phenomena.

Contribution

It introduces a novel model where cosmic ray interactions in the Local Bubble wall account for the neutrino and gamma-ray excesses observed by IceCube and Fermi-LAT.

Findings

CR interactions in the Local Bubble can produce a significant neutrino flux below a few hundred TeV.

The scenario explains the CR flux around the knee.

It links Galactic cosmic ray sources to high-energy astrophysical phenomena.

Abstract

A surprisingly large flux of extraterrestrial high-energy neutrinos was discovered by the IceCube experiment. While the flux of muon neutrinos with energies $E>100$ TeV is consistent with the extragalactic gamma-ray background (EBL) determined by Fermi-LAT, the softer component of the cascade neutrino flux at $E<100$ TeV is larger than expected. Moreover, a gamma-ray excess at high Galactic latitudes at energies $E>300$ GeV was found in the data of Fermi-LAT. The gamma-ray excess at TeV energies and the neutrino excess at $E<100$ TeV may have a common Galactic origin. In this work, we study the possibility that both excesses are caused by interactions of cosmic rays (CRs) with energies up to PeV in the wall of the Local Bubble. Source of these CRs may be a recent nearby source like Vela. We show that such a scenario can explain the observed CR flux around the knee, while CR interactions in the bubble wall can generate a substantial fraction of the observed astrophysical high-energy neutrino flux below $\sim {\rm few} \times 100$ TeV.