  If sterile neutrinos exist and form halos in galactic centers, they can give
rise to observational consequences. In particular, the sterile neutrinos decay
radiatively and heat up the gas in the protogalaxy to achieve hydrostatic
equilibrium, and they provide the mass to form supermassive blackholes. A
natural correlation between the blackhole mass and velocity dispersion thus
arises $\log(M_{BH,f}/M_{\odot})=\alpha \log (\sigma /200 {\rm km s^{-1}})+
\beta$ with $\alpha \approx 4$ and $\beta \approx 8$.
