  The physics of the supernova may provide a clue of the cosmological dark
matter. In the absence of new physics, the supernova calculations do not
explain the observed velocities of pulsars. However, if there exists a singlet
fermion with mass in the 1-20 keV range and a small mixing with neutrinos, this
particle could be emitted asymmetrically from a cooling neutron star in the
event of a supernova explosion. The asymmetry could explain the long-standing
puzzle of pulsar velocities. The same particle could be the dark matter.
Observations of X-ray telescopes, as well as a future detection of
gravitational waves from a nearby supernova can confirm or rule out this
possibility.
