Cosmophysics Seminar ( Dr. Shintaro Eijima )
Sterile neutrino as a possible dark matter candidate is reviewed. I will give an overview of the current status of the research on the dark matter particle, and discuss the motivation and limits obtained through astrophysical observations. Originally the thermal production via mixing was suggested which, however, is ruled out in current constraints. I will introduce different mechanisms to produce the dark matter. In particular a resonant production with lepton asymmetry in thermal plasma and the asymmetry originated by heavy neutral leptons are explained.