Cosmological and astrophysical bounds on a 33.9 MeV sterile neutrino

Abstract In this talk we discuss astrophysical and cosmological bounds on heavy sterile neutrino with mass mvs = 33.9MeV, which was suggested some time ago as a possible interpretation of KARMEN anomaly. Combine experimental data constrain lifetime of this particle in the window ∼ 10−1sec < TS < 150 sec. We show that SN 1987A completely excludes this range of vs lifetime. Nucleosynthesis bound permit a narrow window for the TS around 0.1 sec. If vs possesses an anomalous interaction with nucleons, the SN bounds may not apply, while the nucleosynthesis ones would remain valid.