Čerenkov radiation by neutrinos in a supernova core

Neutrinos with a magnetic dipole moment propagating in a medium with a velocity larger than the phase velocity of light emit photons by the Čerenkov process. The Čerenkov radiation is a helicity flip process via which a lefthanded neutrino in a supernova core may change into a sterile right-handed one and free-stream out of the core. Assuming that the luminosity of such sterile right-handed neutrinos is less than 1053 ergs/sec gives an upper bound on the neutrino magnetic dipole moment μν < 0.2 × 10 μB. This is two orders of magnitude more stringent than the previously established bounds on μν from considerations of supernova cooling rate by right-handed neutrinos. E-mail:[email protected] E-mail:[email protected] PRL-TH-95/10 hep-ph/9506385