Lunar neutrinos

Abstract

Cosmic rays bombard the lunar surface producing mesons, which attenuate inside the regolith. They get slower and decay weakly into mostly sub-GeV neutrinos leaving the surface. Thus the Moon shines in neutrinos. Here we calculate spectra of low-energy neutrinos, which exhibit bright features potentially recognizable above isotropic neutrino background in the direction towards the Moon. Their observation, though a very challenging task for future neutrino large volume experiments, would make the Moon the nearest astrophysical source for which the concept of multimessenger astronomy truly works. Remarkably, some features of the lunar neutrino flux are sensitive to the surface mass density of the Moon.