# Origin of the high energy neutrino flux at IceCube

## TL;DR

This paper analyzes the origins of high-energy neutrinos detected by IceCube, proposing that a spectrum with a slight deviation from E^{-2} and a drop at PeV energies best explains the data, considering various astrophysical sources.

## Contribution

It introduces a neutrino spectrum model with a specific spectral index and features, linking cosmic ray interactions and transport parameters to IceCube observations.

## Key findings

- Diffuse galactic flux accounts for only 2 of 54 events.
- Neutrino flux depends critically on cosmic ray transport parameter δ.
- Proposed E^{-2.1} spectrum with a drop at PeV energies fits IceCube data.

## Abstract

We discuss the spectrum of the different components in the astrophysical neutrino flux reaching the Earth and the possible contribution of each component to the high-energy IceCube data. We show that the diffuse flux from cosmic ray interactions with gas in our galaxy implies just 2 events among the 54 event sample. We argue that the neutrino flux from cosmic ray interactions in the intergalactic (intracluster) space depends critically on the transport parameter $\delta$ describing the energy dependence in the diffusion coefficient of galactic cosmic rays. Our analysis motivates a E^{-2.1} neutrino spectrum with a drop at PeV energies that fits well the data, including the non-observation of the Glashow resonance at 6.3 PeV. We also show that a cosmic ray flux described by an unbroken power law may produce a neutrino flux with interesting spectral features (bumps and breaks) related to changes in the cosmic ray composition.