Sterile neutrino signals from supernovae

We investigate the effects of a mixing of active and sterile neutrinos on the ratios of supernova electron neutrino flux ( F e ) and antineutrino flux ( F ¯ e ) to the total flux of the other neutrino and antineutrino flavors ( F a ). We assume that the heaviest (in the normal hierarchy) standard model neutrino ν 3 mixes with a sterile neutrino resulting in a pair of mass eigenstates with a small mass gap. Using the density matrix formalism we solve numerically the evolution of neutrino states in the envelope of a supernova and determine the flux ratios F e / F a and F ¯ e / F a as a function of the active-sterile mixing angle and for the experimentally allowed range of the standard active-active mixing angle θ 13 .