Speaker
Description
Non-zero rest masses give rise to neutrino flavor oscillations. In addition to the vacuum potential, flavor oscillations depend on the presence of in-medium weakly-interacting particles, including other neutrinos. Within a mean-field treatment of flavor transformation in dense astrophysics environments, this neutrino-neutrino self-interaction term can produce non-linear behavior in the neutrino fields. In core-collapse supernovae and neutron star mergers, the flavor transformation depends on the number and propagation direction of the in-medium neutrinos. Specifically, if the distribution of neutrino flavor has a strong dependence on propagation direction, asymmetries may manifest and cause rapid flavor transformation. These fast-flavor oscillations are on scales much smaller than the hydrodynamical scales of the environment and present a computational challenge. The calculation of the flavor transformation is nominally a 7-dimensional problem, but can be reduced to a smaller number of dimensions by using phase-space moments of the neutrino distributions, thereby lessening the computational cost. We present results from a neutron star merger using a moment-based method for neutrino flavor transformation. Our results show promise that using a moment method could accurately describe the dynamics of fast-flavor oscillations.
