Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. IV. Role of the symmetry energy in pasta phases

TL;DR

This study explores how microscopic corrections influence the role of symmetry energy in the formation of pasta phases in neutron star crusts, showing a diminished impact and lower pasta abundance across various functionals.

Contribution

It extends previous work by analyzing a broader set of functionals and demonstrates that microscopic corrections weaken the correlation between symmetry energy and pasta phase formation.

Findings

Microscopic corrections significantly reduce the influence of symmetry energy.

The correlation between pasta onset density and symmetry energy vanishes with corrections.

Pasta phases are less abundant when microscopic corrections are included.

Abstract

Our previous investigation of neutron-star crusts, based on the functional BSk24, led to a substantial reduction of the pasta mantle when Strutinsky integral and pairing corrections were added on top of the fourth-order extended Thomas-Fermi method (ETF). Here, our earlier calculations are widened to a larger set of functionals within the same family, and we find that the microscopic corrections weaken significantly the influence of the symmetry energy. In particular, the correlation observed at the pure ETF level between the density for the onset of pasta formation and the symmetry energy vanishes, not only for the $L$ coefficient but also for the symmetry-energy values at the relevant densities. Moreover, the inclusion of microscopic corrections results in a much lower abundance of pasta for all functionals.