Formation of Nuclear "Pasta" in Supernovae

TL;DR

This paper uses quantum molecular dynamics simulations to demonstrate the formation of nuclear pasta phases, such as rod-like and layered structures, in collapsing supernova cores, revealing the transition process from spherical nuclei to complex lattice structures.

Contribution

It provides the first ab-initio simulation evidence that nuclear pasta phases form from initial bcc lattices during supernova core collapse.

Findings

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

Elongated nuclei undergo zigzag configuration during transition.

Fusion of spherical nuclei leads to pasta phase formation.

Abstract

In supernova cores, nuclear "pasta" phases such as triangular lattice of rod-like nuclei and layered structure of slab-like nuclei are considered to exist. However, it is still unclear whether or not they are actually formed in collapsing supernova cores. Using {\it ab-initio} numerical simulations called the Quantum Molecular Dynamics (QMD), we here solve this problem by demonstrating that a lattice of rod-like nuclei is formed from a bcc lattice by compression. We also find that, in the transition process, the system undergoes zigzag configuration of elongated nuclei, which are formed by a fusion of two original spherical nuclei.