Neutrinos from Extra-Large Hadron Collider in the Milky Way

TL;DR

This paper demonstrates that a significant portion of TeV-PeV neutrinos detected by IceCube originate from the Milky Way, with their spectra aligning with cosmic ray models and gamma-ray observations, revealing insights into Galactic cosmic ray processes.

Contribution

It establishes a connection between neutrino signals and Galactic cosmic rays, providing spectral analysis that supports diffusive shock acceleration models and cosmic ray variability explanations.

Findings

Galactic contribution to IceCube neutrinos is significant.

Galactic cosmic ray spectrum follows a power-law with slope ~2.45.

Local cosmic ray spectrum is softer than the Galactic average.

Abstract

Neutrino telescope IceCube has recently discovered astrophysical neutrinos with energies in the TeV-PeV range. We use the data of Fermi gamma-ray telescope to demonstrate that the neutrino signal has significant contribution from the Milky Way galaxy. Matching the gamma-ray and neutrino spectra we find that TeV-PeV Galactic cosmic rays form a powerlaw spectrum with the slope p~2.45. This spectral slope is consistent with the average cosmic ray spectrum in the disks of the Milky Way and Large Magellanic Cloud galaxies. It is also consistent with the theoretical model of cosmic ray injection by diffusive shock acceleration followed by escape through the Galactic magnetic field with Kolmogorov turbulence. The locally observed TeV-PeV cosmic ray proton spectrum is softer than the average Galactic cosmic ray spectrum. This could be readily explained by variability of injection of cosmic rays in the local interstellar medium over the past 1e7 yr and discreetness of the cosmic ray source distribution.