Neutrino Signals from Muon Decay in Neutron Stars
Toby Opferkuch (UC Berkeley and LBNL)

Neutrino emission plays an important role in the cooling of neutron stars. Thermally emitted neutrinos, however, have sub-MeV energies and are therefore all but impossible to detect from such distant sources. In this talk I will argue that neutron stars should emit a secondary, non-thermal, neutrino flux arising from out-of-equilibrium muon decays. Muons are abundant in the core of the star, but due to the large electron chemical potential, their decay is initially prevented by Pauli blocking. Over timescales of order years, however, they can diffuse outwards into regions of low electron chemical potential, where their decay becomes possible and results in a flux of neutrinos with energies up to 40 MeV. While detecting this flux from a single neutron star is challenging, the integrated flux from all neutron stars in the Milky Way is comparable to the diffuse supernova neutrino background, it may be observable in next-generation detectors like DUNE and HyperKamiokande. This would offer a unique new way of probing the inner structure of neutron stars.