Speaker
Description
Binary neutron star mergers (BNSMs) generate neutron-rich outflows that power r-process nucleosynthesis and kilonova emission. In these environments, intense neutrino radiation determines the electron fraction of the ejecta. Neutrino self-interactions can induce collective flavor transformation, including matter–neutrino resonance (MNR), which occurs when the neutrino self-interaction potential cancels the matter potential in antineutrino-dominated conditions.
We investigate MNR using two complementary approaches: linear stability analysis (LSA) and fully time-dependent quantum kinetic simulations. The simulations solve the time evolution of the flavor density matrix in anisotropic neutrino backgrounds, allowing us to follow the nonlinear development of flavor conversion.
The linear stability analysis is performed independently on inhomogeneous matter and neutrino profiles. Unlike many previous works that assume homogeneous backgrounds, our LSA explicitly includes spatial variations of the matter and neutrino potentials. Realistic distributions extracted from simulations are used to construct physically motivated background models for the stability analysis.
By comparing instability conditions from LSA with the dynamical behavior seen in time-dependent simulations, we clarify under what physical circumstances MNR can arise and how it evolves in merger outflows. This work provides a more realistic assessment of flavor instabilities in BNSM environments.