Fast neutrino cooling of nuclear pasta in neutron stars: molecular dynamics simulations

TL;DR

This paper demonstrates through molecular dynamics simulations that nuclear pasta phases in neutron star crusts significantly enhance neutrino emission via direct URCA processes, potentially dominating neutron star cooling.

Contribution

It models various nuclear pasta phases with large-scale simulations, revealing their substantial role in neutrino emission and neutron star cooling.

Findings

Neutrino luminosity from pasta can be 3-4 orders of magnitude higher than from modified URCA.

Nuclear pasta phases enable direct URCA reactions by satisfying momentum conservation.

Neutrino radiation from pasta may significantly influence neutron star thermal evolution.

Abstract

The direct URCA process of rapid neutrino emission can occur in nonuniform nuclear pasta phases that are expected in the inner crust of neutron stars. Here, the periodic potential for a nucleon in nuclear pasta allows momentum conservation to be satisfied for direct URCA reactions. We improve on earlier work by modeling a rich variety of pasta phases (gnocchi, waffle, lasagna, and anti-spaghetti) with large-scale molecular dynamics simulations. We find that the neutrino luminosity due to direct URCA reactions in nuclear pasta can be 3 to 4 orders of magnitude larger than that from the modified URCA process in the NS core. Thus neutrino radiation from pasta could dominate radiation from the core and this could significantly impact the cooling of neutron stars