Neutrino Flavor Conversion, Advection, and Collisions: Towards the Full Solution

Understand

At high densities in compact astrophysical sources, the coherent forward scattering of neutrinos onto each other is responsible for making the flavor evolution non-linear.

• Under the assumption of spherical symmetry, we present the first simulations tracking flavor transformation in the presence of neutrino-neutrino forward scattering, neutral and charged current collisions with the matter background, as well as neutrino advection.
• We find that, although flavor equipartition could be one of the solutions, it is not a generic outcome, as often postulated in the literature.
• Intriguingly, the strong interplay between flavor conversion, collisions, and advection leads to a spread of flavor conversion across the neutrino angular distributions and neighboring spatial regions.