Hidden Cosmic-Ray Accelerators as an Origin of TeV-PeV Cosmic Neutrinos

TL;DR

This paper argues that the sources of TeV-PeV cosmic neutrinos are likely hidden cosmic-ray accelerators that are opaque to gamma rays, based on multimessenger constraints from neutrino and gamma-ray observations.

Contribution

It introduces a multimessenger framework to identify hidden cosmic-ray accelerators as the origin of high-energy neutrinos, considering gamma-ray opacity constraints.

Findings

Sources are likely opaque to 1-100 GeV gamma rays.

Gamma-ray observations challenge transparent source models.

Neutrino data suggest hidden, dense source environments.

Abstract

The latest IceCube data suggest that the all-flavor cosmic neutrino flux may be as large as 10^-7 GeV/cm^2/s/sr around 30 TeV. We show that, if sources of the TeV-PeV neutrinos are transparent to gamma rays with respect to two-photon annihilation, strong tensions with the isotropic diffuse gamma-ray background measured by Fermi are unavoidable, independently of the production mechanism. We further show that, if the IceCube neutrinos have a photohadronic (pgamma) origin, the sources are expected to be opaque to 1-100 GeV gamma rays. With these general multimessenger arguments, we find that the latest data suggest a population of cosmic-ray accelerators hidden in GeV-TeV gamma rays as a neutrino origin. Searches for x-ray and MeV gamma-ray counterparts are encouraged, and TeV-PeV neutrinos themselves will serve as special probes of dense source environments.