Production of unstable heavy neutrinos in proto-neutron stars

We discuss the production of a class of heavy sterile neutrinos νhνh in proto-neutron stars. The neutrinos, of mass around 50 MeV50 MeV, have a negligible mixing with the active species but relatively large dimension-5 electromagnetic couplings. In particular, a magnetic dipole moment μ≈10−6 GeV−1μ≈10−6 GeV−1 implies that they are thermally produced through e+e−→ν¯hνh in the early phase of the core collapse, whereas a heavy–light transition moment μtr≈10−8 GeV−1μtr≈10−8 GeV−1 allows their decay νh→νiγνh→νiγ with a lifetime around 10−3 s10−3 s. This type of electromagnetic couplings has been recently proposed to explain the excess of electron-like events in baseline experiments. We show that the production and decay of these heavy neutrinos would transport energy from the central regions of the star to distances d≈400 kmd≈400 km, providing a very efficient mechanism to enhance the supernova shock front and heat the material behind it.