Neutrino Flavor Evolution in Binary Neutron Star Merger Remnants

TL;DR

This paper investigates how neutrino flavor transformations in binary neutron star merger remnants influence nucleosynthesis, using simulation-based emission data and a single-trajectory approach to understand flavor evolution effects.

Contribution

It introduces a detailed study of neutrino flavor evolution in merger remnants with simulation-based emission profiles and assesses its impact on nucleosynthesis.

Findings

Flavor conversion affects neutrino absorption rates.

Flavor evolution depends on emission location and angle.

Results are sensitive to emission characteristics from simulations.

Abstract

We study the neutrino flavor evolution in the neutrino-driven wind from a binary neutron star merger remnant consisting of a massive neutron star surrounded by an accretion disk. With the neutrino emission characteristics and the hydrodynamical profile of the remnant consistently extracted from a three-dimensional simulation, we compute the flavor evolution by taking into account neutrino coherent forward scattering off ordinary matter and neutrinos themselves. We employ a "single-trajectory" approach to investigate the dependence of the flavor evolution on the neutrino emission location and angle. We also show that the flavor conversion in the merger remnant can affect the (anti-)neutrino absorption rates on free nucleons and may thus impact the $r$-process nucleosynthesis in the wind. We discuss the sensitivity of such results on the change of neutrino emission characteristics, also from different neutron star merger simulations.