Executive Summary : | The next Galactic supernova SN will be a lifetime event for particle astrophysics, offering a unique opportunity for a multi-messenger detection of gravitational waves, neutrinos of all flavors and multi-wavelength photons. In this context, the role of quotastrophysical messengersquot played by supernova neutrinos is largely associated with the signatures imprinted on the observable neutrino burst by the flavor conversions occurring deep inside the star. In this regard SNe are unique astrophysical environments where the neutrino density is so high to provide a relevant background for neutrino propagation and flavor evolution, causing nonlinear feedback effects. The resulting “self-induced flavor conversions†would reshuffle the neutrino flavor among different momentum modes. The main effects are driven by collective run-away modes of the self-interacting neutrino gas, that can spontaneously break the initial symmetries of the flavor evolution such as axial symmetry, homogeneity, isotropy and even stationarity. The NU FEEDBACK plans to bring the current theory of nonlinear flavor oscillations in a SN to a new level of understanding, by means of advanced numerical and analytical techniques. The feedback of the nonlinear flavor changes on the SN dynamics, on stellar nucleosynthesis, and on the observable neutrino signal from a SN will be investigated. We also plan to extend the investigations of nonlinear flavor conversions to accretion disks formed by binary neutron-star BNS mergers. Even if the detection perspectives of a BNS neutrino burst are less promising than in the SN case, the dynamics of such an astrophysical environment is expected to be affected by the large huge flux emitted by the coalescing stars. |