The supernova ( SN ) neutronization phase produces mainly electron ( \nu _ { e } ) neutrinos , the oscillations of which must take place within a few mean-free-paths of their resonance surface located nearby their neutrinosphere .
The state-of-the-art on the SN dynamics suggests that a significant part of these \nu _ { e } can convert into right-handed neutrinos in virtue of the interaction of the electrons and the protons flowing with the SN outgoing plasma , whenever the Dirac neutrino magnetic moment be of strength \mu _ { \nu } < 10 ^ { -11 } \mu _ { B } , with \mu _ { B } being the Bohr magneton .
In the supernova envelope , part of these neutrinos can flip back to the left-handed flavors due to the interaction of the neutrino magnetic moment with the magnetic field in the SN expanding plasma ( Kuznetsov & Mikheev 2007 ; Kuznetsov , Mikheev & Okrugin 2008 ) , a region where the field strength is currently accepted to be B \gtrsim 10 ^ { 13 } G. This type of \nu oscillations were shown to generate powerful gravitational wave ( GW ) bursts ( Mosquera Cuesta 2000 , Mosquera Cuesta 2002 , Mosquera Cuesta & Fiuza 2004 , Loveridge 2004 ) .
If such double spin-flip mechanism does run into action inside the SN core , then the release of both the oscillation-produced \nu _ { \mu } s , \nu _ { \tau } s and the GW pulse generated by the coherent \nu spin-flips provides a unique emission offset \Delta T ^ { emission } _ { GW } \leftrightarrow \nu = 0 for measuring the \nu travel time to Earth .
As massive \nu s get noticeably delayed on its journey to Earth with respect to the Einstein GW they generated during the reconversion transient , then the accurate measurement of this time-of-flight delay by SNEWS + LIGO , VIRGO , BBO , DECIGO , etc. , might readily assess the absolute \nu mass spectrum .