Heavier and Cooler Sterile Neutrino Dark Matter

A mechanism for generating the relic density of sterile neutrinos, which could serve as dark matter, is discussed. In the described scenario, a population of “heavy” sterile neutrinos is initially produced via scattering-induced decoherence of active neutrinos. Subsequently, this population is transferred to one (or more) lighter sterile neutrinos through scatterings and decays mediated by (“secret”) self-interactions among sterile neutrinos. These lighter neutrinos exhibit either very weak or no mixing with active neutrinos and have the potential to serve as dark matter with masses ranging from approximately 10 keV to 1 GeV. As such, they can bypass existing constraints; however, they might still be detectable in future observations.