Astrophysical and cosmological constraints to neutrino properties

Since the 1970s with the establishment of the big bang model, it ha become clear that some of the most restrictive constraints on certain neutrino properties come from astrophysical and cosmological considerations. Furthermore, in 1987 the detection of neutrinos from the supernova in the Large Megellanic Cloud provided a new neutrino laboratory as well as confirming our basic understanding of gravitational collapse energetics. In this paper, the authors review those constraints on neutrinos derived from cosmological and astrophysical considerations. The authors first examine the freeze-out of neutrinos in the early universe and derive the cosmological limits on masses for stable neutrinos. The authors then use the freeze-out arguments coupled with observational limits to constrain decaying neutrinos as well. The authors also review the limits to neutrino properties that follow from SN 1987A. The authors then look at the constraint from big bang nucleosynthesis on the number of neutrino flavors. Before ending, the authors briefly look at astrophysical constraints on neutrino mixing as well as future astronomical observations of relevance to neutrino physics