Influence of neutrino-electron scattering and neutrino-pair annihilation on hypermassive neutron star

TL;DR

This study examines how inelastic neutrino microphysics, especially neutrino-electron scattering, affects the dynamics and ejecta in hypermassive neutron star simulations, revealing significant impacts on disc mass, ejecta, and neutrino luminosities.

Contribution

It introduces the inclusion of inelastic neutrino-electron scattering into general-relativistic magnetohydrodynamics simulations of hypermassive neutron stars, showing its substantial effects.

Findings

75% higher disc mass with neutrino-electron scattering

18% more ejected mass due to inelastic scattering

Neutrino luminosities increased by 30-50% for various neutrino types

Abstract

We investigate the influence of inelastic neutrino microphysics in general-relativistic magnetohydrodynamics simulations of a hypermassive neutron star. In particular, we include species/energy groups coupled neutrino-matter interactions, such as inelastic neutrino-electron scattering and electron-positron annihilation kernels, into simulations up to 50 ms. Neutrino-electron inelastic scattering is known to have effective neutrino-matter energy exchange. We show that, with neutrino-electron inelastic scattering, simulations predict 75% higher disc mass with slightly different mass-averaged compositions, and 18% more ejected mass with similar distributions. The enhancement of the mass of the disc and the ejecta results in stronger baryon pollution, leading to less favourable jet launching environments. Furthermore, neutrino luminosities are about 50, 40, and 30% higher for electron neutrino, electron anti-neutrino, and heavy-lepton neutrinos. In contrast, we do not see any significant impacts due to electron-positron annihilation.