Supernova Bounds on Resonant Active-Sterile Neutrino Conversions

We discuss the effects of resonant ${\nu }_e\to {\nu }_s$ and $\bar{\nu}_e \to \bar{\nu}_s$($\nu_s$ is a sterile neutrino) conversions in the dense medium of a supernova. In particular, we assume the sterile neutrino ${\nu }_s$ to be in the hot dark matter few eV mass range. The implications of such a scenario for the supernova shock re-heating, the detected ${\bar{\nu }}_e$ signal from SN1987A and for the r-process nucleosynthesis hypothesis are analysed in some detail. The resulting constraints on mixing and mass difference for the ${\nu }_e-{\nu }_s$ system are derived. There is also an allowed region in the neutrino parameter space for which the r-process nucleosynthesis can be enhanced.