Resonant Production of Sterile Neutrinos in the Early Universe

We examine the cosmological impacts of a light resonantly produced sterile neutrino in the early universe. Such a neutrino could be produced through lepton number-driven Mikheyev-Smirnov-Wolfenstein conversion of active neutrinos, resulting in a non-thermal spectrum of both sterile and active neutrinos. If this process occurs during weak decoupling and big bang nucleosynthesis, it would affect the electron neutrino flux and therefore the n/p ratio. This allows us to use observations of primordial helium (Yp), primordial deuterium (D/H), and Neff to place limits on this process