Sterile neutrino signals from supernovae

Abstract

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 (${F}_{\overline{e}}$) 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 ${\ensuremath{\nu}}_{3}$ 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 ${F}_{\overline{e}}/{F}_{a}$ as a function of the active-sterile mixing angle and for the experimentally allowed range of the standard active-active mixing angle ${\ensuremath{\theta}}_{13}$.