The Neutrino Magnetic Moment Portal and Supernovae: New Constraints and Multimessenger Opportunities

TL;DR

This paper explores how sterile neutrinos interacting via magnetic moments could be produced in supernovae, leading to detectable signals, and establishes new constraints on their properties based on supernova observations and future experiment sensitivities.

Contribution

It provides the first comprehensive analysis of supernova and diffuse flux constraints on magnetic-moment sterile neutrinos across a broad mass range, highlighting new bounds and detection prospects.

Findings

Non-observation of signals from SN1987A sets strong constraints on sterile neutrinos with 0.1-100 MeV masses.

Future experiments like Fermi-LAT, DUNE, and Hyper-Kamiokande can improve sensitivity to these sterile neutrinos.

Diffuse flux analysis constrains sterile neutrinos in the 1-100 keV mass range, surpassing previous bounds.

Abstract

We scrutinize the hypothesis that gauge singlet fermions -- sterile neutrinos -- interact with Standard Model particles through the transition magnetic moment portal. These interactions lead to the production of sterile neutrinos in supernovae followed by their decay into photons and active neutrinos which can be detected at $\gamma$-ray telescopes and neutrino detectors, respectively. We find that the non-observation of active neutrinos and photons from sterile-neutrino decay associated to SN1987A yields the strongest constraints to date on magnetic-moment-coupled sterile neutrinos if their masses are inside a $0.1-100$ MeV window. Assuming a near-future galactic supernova explosion, we estimate the sensitivity of several present and near-future experiments, including Fermi-LAT, e-ASTROGAM, DUNE, and Hyper-Kamiokande, to magnetic-moment-coupled sterile neutrinos. We also study the diffuse photon and neutrino fluxes produced in the decay of magnetic-moment coupled sterile neutrinos produced in all past supernova explosions and find that the absence of these decay daughters yields the strongest constraints to date for sterile neutrino masses inside a $1-100$ keV window.