A reduction in the UHE neutrino flux due to neutrino spin precession

TL;DR

This paper investigates how ultra-high-energy neutrinos from astrophysical sources might oscillate into sterile states due to magnetic moments, potentially reducing observable fluxes.

Contribution

It introduces the possibility that neutrino spin precession caused by a magnetic moment can significantly diminish UHE neutrino fluxes from astrophysical sources.

Findings

Neutrino magnetic moments as small as 1E-15 mu_B can induce oscillations.

Intense magnetic fields in sources facilitate neutrino spin precession.

Such oscillations could explain the low flux limits observed.

Abstract

Motivated by the stringent flux limits for UHE neutrinos coming from gamma ray burst or active galactic nuclei, we explore the possibility that the active neutrinos generated in such astrophysical objects could oscillate to sterile right handed states due to a neutrino magnetic moment mu_nu. We find that a value as small as mu_nu ~1E-15 mu_B could produce such a transition thanks to the intense magnetic fields that are expected in these objects.