Heavy sterile neutrinos: Bounds from big-bang nucleosynthesis and SN 1987A

Abstract

Cosmological and astrophysical effects of heavy (10 - 200 MeV) sterile Dirac neutrinos, mixed with the active ones, are considered. The bounds on mass and mixing angle from both supernovae and big-bang nucleosynthesis are presented.

Comments: 19 pages, 5 figures, 1 table. Some references added