Neutrinos and Flavor Change
Almost all of the energy from core-collapse supernovae is radiated in the form of neutrinos. This emission is key to both the explosion mechanism itself and to many of the subsequent observables, including the nucleosynthesis. Neutrinos were observed in the case of Supernova 1987a which exploded in the Large Magellanic Cloud. There are several large, underground neutrino detectors (e.g. Super-K and IceCube) are currently operational, and others are planned in the near future (e.g. DUNE), increasing our confidence that a high-statistics SN neutrino signal will eventually be observed.
Observations of supernova neutrinos will shed important light on the physics of the proto-neutron star at the center of a core-collapse supernovae. These observations also have the potential to teach us important lessons about neutrinos themselves. Many properties of neutrinos are now known, including the mass-squared mass differences and vacuum mixing angles. But, the detection of neutrinos from a Galactic core-collapse supernovae (or neutron star merger) could reveal the neutrino mass hierarchy, their Dirac or Majorana nature, and the possibility of sterile states.