Influence of light nuclei on neutrino-driven supernova outflows

TL;DR

This study investigates the composition of protoneutron star outer layers, highlighting the presence of light nuclei and their subtle effects on neutrino energies, which influence supernova nucleosynthesis.

Contribution

It provides new insights into the role of light nuclei in supernova outflows and their impact on neutrino energy spectra during different post-explosion phases.

Findings

Light nuclei are abundant in protoneutron star outer layers.

Light nuclei slightly increase electron antineutrino energy early on.

They reduce electron antineutrino energy by about 1 MeV during cooling.

Abstract

We study the composition of the outer layers of a protoneutron star and show that light nuclei are present in substantial amounts. The composition is dominated by nucleons, deuterons, tritons and alpha particles; 3He is present in smaller amounts. This composition can be studied in laboratory experiments with new neutron-rich radioactive beams that can reproduce similar densities and temperatures. After including the corresponding neutrino interactions, we demonstrate that light nuclei have a small impact on the average energy of the emitted electron neutrinos, but are significant for the average energy of antineutrinos. During the early post-explosion phase, the average energy of electron antineutrinos is slightly increased, while at later times during the protoneutron star cooling it is reduced by about 1 MeV. The consequences of these changes for nucleosynthesis in neutrino-driven supernova outflows are discussed.