Low-energy probes of sterile neutrino transition magnetic moments

Sterile neutrinos with keV-MeV masses and non-zero transition magnetic moments can be probed through low-energy nuclear or electron recoil measurements. Here we determine the sensitivities of current and future searches, showing how they can probe a previously unexplored parameter region. Future coherent elastic neutrino-nucleus scattering (CE$\nu$NS) or elastic neutrino-electron scattering (E$\nu$ES) experiments using a monochromatic $^{51}$Cr source can fully probe the region indicated by the recent XENON1T excess.
Comment: 22 pages, 4 figures, 2 tables. V2: References added, Fig.3 updated with additional bounds, conclusions unchanged, matches the published version