Nuclear pasta in hot dense matter and its implications for neutrino scattering

TL;DR

This paper investigates how finite temperature effects cause nuclear pasta structures in neutron-rich matter to dissolve at around 4 MeV, affecting neutrino scattering and implications for supernovae and neutron star mergers.

Contribution

It provides the first detailed analysis of pasta melting temperatures near beta-equilibrium and their impact on neutrino opacity in astrophysical environments.

Findings

Pasta structures dissolve at T_m^β ≈ 4 MeV near beta-equilibrium.

Coherent neutrino scattering from pasta modestly influences neutrino opacity.

Pasta melting temperature is sensitive to proton fraction.

Abstract

We find that the abundance of large clusters of nucleons in neutron-rich matter at sub-nuclear density is greatly reduced by finite temperature effects when matter is close to beta-equilibrium. Large nuclei and exotic non-spherical nuclear configurations called pasta, favored in the vicinity of the transition to uniform matter at $T=0$, dissolve at relatively low temperature. For matter close to beta-equilibrium we find that the pasta melting temperature is $T_m^\beta\simeq 4\pm 1$~MeV for realistic equations of state. The mechanism for pasta dissolution is discussed, and in general $T_m^\beta$ is shown to be sensitive to the proton fraction. We find that coherent neutrino scattering from nuclei and pasta makes a modest contribution to the opacity under the conditions encountered in supernovae and neutron star mergers. Implications for neutrino signals from galactic supernovae are briefly discussed.