Resonant Spin-Flavor Precession of Sterile Neutrinos

We analyze the impact of resonant conversions mediated by non-vanishing magnetic moments between active neutrinos and a heavy sterile neutrino on the supernova neutrino flux. We present the level-crossing scheme for such a scenario and derive the neutrino fluxes after conversion, paying particular attention to the order in which the resonances occur. We then compute the expected event rates from the neutronization burst of a future supernova at DUNE and Hyper-Kamiokande to derive new constraints on the neutrino magnetic moment. With this, we find a sensitivity down to a few ${10}^{-15}{\mu }_B$ for a sterile neutrino in the $O(\mathrm{e}\mathrm{V})$ mass range.