Crust of accreting neutron stars within simplified reaction network

Abstract

Transiently accreting neutron stars in low mass X-ray binaries are generally believed to be heated up by nuclear reactions in accreted matter during hydrostatic compression. Detailed modeling of these reactions is required for the correct interpretation of observations. In this paper, we construct a simplified reaction network, which can be easily implemented and depends mainly on atomic mass tables as nuclear physics input. We show that it reproduces results of the detailed network by Lau et al. (2018) very well, if one applies the same mass model. However, the composition and the heating power are shown to be sensitive to the mass table used and treatment of mass tables boundary, if one applies several of them in one simulation. In particular, the impurity parameter $Q_{\mathrm{imp}}$ at density $\rho =2\times 10^{12}$ g cm${}^{-3}$ can differ for a factor of few, and even increase with density increase. The profile of integrated heat realize shown to be well confined between results by Fantina et al. (2018) and Lau et al. (2018).

Accepted for publication in MNRAS, 10 pages, 8 figures

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• Crucial role of neutron diffusion in the crust of accreting neutron stars
• Accreting neutron stars: heating of the upper layers of the inner crust
• Phase diagrams of binary ionic mixtures and white dwarf cooling
• Accreting neutron stars: composition of the upper layers of the inner crust
• Accreting neutron stars from the nuclear energy-density functional theory. II. Equation of state and global properties
• The Impact of Neutron Transfer Reactions on Heating and Cooling of Accreted Neutron Star Crusts
• Nonequilibrium thermodynamics of accreted neutron-star crust
• Impact of Pycnonuclear Fusion Uncertainties on the Cooling of Accreting Neutron Star Crusts
• Constraining Accreted Neutron Star Crust Shallow Heating with the Inferred Depth of Carbon Ignition in X-ray Superbursts
• Breaking properties of multicomponent neutron star crust
• Layers of electron captures in the crust of accreting neutron stars