Neutrino signal from proto-neutron star evolution: Effects of opacities from charged-current-neutrino interactions and inverse neutron decay

TL;DR

This paper examines how charged-current neutrino interactions and inverse neutron decay influence neutrino spectra during proto-neutron star evolution, with implications for nucleosynthesis in neutrino-driven winds.

Contribution

It develops a comprehensive model including weak magnetism and inelastic processes, and assesses the impact of inverse neutron decay on neutrino spectra during proto-neutron star deleptonization.

Findings

Inverse neutron decay dominates low-energy antineutrino opacity.

Weak magnetism significantly affects neutrino luminosities and energies.

Accurate neutrino transport links reaction details to nucleosynthesis conditions.

Abstract

We investigate the impact of charged current neutrino processes on the formation and evolution of neutrino spectra during the deleptonization of proto-neutron stars. To this end we develop the full kinematics of these reaction rates consistent with the nuclear equation of state, including weak magnetism contributions. This allows us to systematically study the impact of inelastic contributions and weak magnetism on the $\nu_e$ and $\bar\nu_e$ luminosities and average energies. Furthermore, we explore the role of the inverse neutron decay, also known as the direct Urca process, on the emitted spectra of $\bar\nu_e$. This process is commonly considered in the cooling scenario of cold neutron stars but has so far been neglected in the evolution of hot proto-neutron stars. We find that the inverse neutron decay becomes the dominating opacity source for low-energy $\bar\nu_e$. Accurate three-flavor Boltzmann neutrino transport enables us to relate the magnitude of neutrino fluxes and spectra to details of the treatment of weak processes. This allows us to quantify the corresponding impact on the conditions relevant for the nucleosynthesis in the neutrino-driven wind, which is ejected from the proto-neutron star surface during the deleptonization phase.