Simulating pasta phases by molecular dynamics and cold atoms --- Formation in supernovae and superfluid neutrons in neutron stars

TL;DR

This paper demonstrates the formation of nuclear pasta phases in dense stellar environments through molecular dynamics simulations, revealing the process triggers by attractive forces rather than fission instability, and explores connections to ultracold Fermi gases.

Contribution

It provides the first simulation-based evidence of pasta phase formation in supernova cores and neutron stars, highlighting the role of attractive forces between nuclei.

Findings

Lattice of rod-like nuclei forms from bcc lattice by compression.

Formation triggered by attractive forces between nuclei, not fission instability.

Discusses connection between neutron star pasta phases and ultracold Fermi gases.

Abstract

In dense stars such as collapsing cores of supernovae and neutron stars, nuclear "pasta" such as rod-like and slab-like nuclei are speculated to exist. However, whether or not they are actually formed in supernova cores is still unclear. Here we solve this problem by demonstrating that a lattice of rod-like nuclei is formed from a bcc lattice by compression. We also find that the formation process is triggered by an attractive force between nearest neighbor nuclei, which starts to act when their density profile overlaps, rather than the fission instability. We also discuss the connection between pasta phases in neutron star crusts and ultracold Fermi gases.