Fluctuations in the pasta phase

TL;DR

This paper investigates the complex inhomogeneous pasta phase in baryonic matter near saturation density, analyzing how temperature, density, and composition fluctuations influence the coexistence of different geometries and their effects on neutron star properties.

Contribution

It introduces a statistical multi-component approach with a realistic energy functional to model pasta phase composition considering fluctuations in geometry, density, and proton fraction.

Findings

Different pasta geometries can coexist over a wide temperature range.

Charge fluctuations in the pasta phase are quantitatively estimated.

Coexistence persists down to the crust crystallization temperature.

Abstract

Baryonic matter close to the saturation density is very likely to present complex inhomogeneous structures collectively known under the name of pasta phase. At finite temperature, the different geometric structures are expected to coexist, with potential consequences on the neutron star crust conductivity and neutrino transport in supernova matter. In the framework of a statistical multi-component approach, we calculate the composition of matter in the pasta phase considering density, proton fraction, and geometry fluctuations. Using a realistic energy functional from relativistic mean field theory and a temperature and isospin dependent surface tension fitted from Thomas-Fermi calculations, we show that different geometries can coexist in a large fraction of the pasta phase, down to temperatures of the order of the crystallization temperature of the neutron star crust. Quantitative estimates of the charge fluctuations are given.