Collisional and Fast Neutrino Flavor Instabilities in Two-dimensional Core-collapse Supernova Simulation with Boltzmann Neutrino Transport

Understand

We present a comprehensive study on the occurrences of the collisional flavor instability (CFI) and the fast flavor instability (FFI) of neutrinos based on a two-dimensional (2D) core-collapse supernova (CCSN) simulation performed with a Boltzmann radiation hydrodynamics code.

• We find that CFI occurs in a region with the baryon-mass density of $10^{10}\lesssim \rho \lesssim 10^{12}\,\mathrm{g}\,\mathrm{cm}^{-3}$, which is similar to the previous results in one-dimensional (1D) CCSN models.
• In contrast to 1D, however, the CFI region varies with time vigorously in the 2D model, whereas it had a quiescent structure in 1D.
• This is attributed to the fact that the turbulent flows advected from a gain region account for the temporal variations.