Unified equations of state for cold nonaccreting neutron stars with Brussels-Montreal functionals. III. Inclusion of microscopic corrections to pasta phases

Abstract

Earlier fourth-order extended Thomas-Fermi calculations with functional BSk24 of pasta phases in the inner crust of neutron stars are here repeated with Strutinsky-integral and pairing corrections included for protons. The main consequence of these corrections is to eliminate the spaghetti phase at zero temperature and significantly reduce the range of densities over which the lasagna phase is found. On the other hand, the microscopic corrections have a negligible impact on the equation of state and on the proton fraction.

Onset of Electron Captures and Shallow Heating in Magnetars

“…Full numerical results can be found in [45]. Together with the results for the equation of state and superfluid properties published in [15][16][17][18]43], they provide consistent microscopic inputs for modelling the magneto-thermal evolution of neutron stars.…”

“…The functional BSk24 underlying the model HFB-24 was also adopted to calculate the equation of state of the inner crust of a magnetar [18]. This same functional was also applied to construct a unified equation of state for unmagnetized neutron stars [15][16][17], and to calculate superfluid properties [43]. Results are publicly available on CompOSE 2 .…”

“…Results are presented based on experimental nuclear data supplemented with the Brussels-Montreal atomic mass table HFB-24 [14]. The underlying nuclear energy-density functional BSk24 has been already applied to construct unified equations of state for both unmagnetized neutron stars [15][16][17] and magnetars [18].…”

Accreting neutron stars from the nuclear energy-density functional theory

“…We We further assumed that nuclear clusters remain spherical and we calculated the Coulomb energy in the WS approximation. Indeed, the presence of so-called nuclear 'pasta' has recently been found to be marginal within the ETFSI approach (Pearson & Chamel 2022). In order to further reduce the computation time, the nucleon density distributions in the WS cell were parametrised as n q (r) = n Bq + n Λq f q (r), where q = n, p for neutrons and protons respectively, r is the radial distance from the centre of the spherical cell, n Bq is the background density, and the second term accounts for the presence of inhomogeneities, with n Λq a constant term and f q (r) a damped Fermi function ensuring that density derivatives vanish at the surface of the cell, thus providing a smooth matching of the nucleon distributions between adjacent cells (Onsi et al 2008).…”

Inner crust equations of state for CompOSE

“…Pairing effects in the inner crust have also been discussed, check e.g. [22][23][24][25][26][27] and references therein. Pairing may have some effects on the structure (geometries) in the crust, but overall the effect on the EoS is negligible [22].…”