Transport properties of nuclear pasta phase with quantum molecular dynamics

TL;DR

This study uses quantum molecular dynamics to analyze the transport properties of nuclear pasta phases, revealing that these phases do not significantly impede thermal, electrical, or viscous transport compared to inner crust matter in neutron stars.

Contribution

It provides the first comprehensive simulation-based estimates of shear viscosity, electrical, and thermal conductivities of nuclear pasta across various densities, temperatures, and proton fractions.

Findings

Transport coefficients are similar in magnitude to those in neutron star crusts without pasta.

Irregularities in the static structure factor do not greatly affect transport properties.

Presence of slab phases enhances peaks in the static structure factor.

Abstract

We study the transport properties of nuclear pasta for a wide range of density, temperature and proton fractions, relevant for different astrophysical scenarios adopting a quantum molecular dynamics model. In particular, we estimate the values of shear viscosity as well as electrical and thermal conductivities by calculating the static structure factor $S(q)$ using simulation data. In the density and temperature range where the pasta phase appears, the static structure factor shows irregular behavior. The presence of a slab phase greatly enhances the peak in $S(q)$. However, the effect of irregularities in $S(q)$ on the transport coefficients is not very dramatic. The values of all three transport coefficients are found to have the same orders of magnitude as found in theoretical calculations for the inner crust matter of neutron stars without the pasta phase and therefore, is in contrast to earlier speculations that a pasta layer might be highly resistive, both thermally and electrically.