Radiatively Decaying Neutrinos and Photoionization of the Universe at High Redshifts

摘要

It is shown that the ionization state of the diffuse IGM, as required by the GP tests, can be explained without violating any other astrophysical or cosmological constraint on the model. We also investigate the implications of recently observed resonant neutral helium lines at z ≈2 on the radiatively decaying neutrino scenario; this observation rules out almost all of the parameter space for neutrino masses ≥50 eV.