The Impact of Neutron Transfer Reactions on Heating and Cooling of Accreted Neutron Star Crusts

Abstract

Nuclear reactions heat and cool the crust of accreting neutron stars and need to be understood to interpret observations of X-ray bursts and of long-term cooling in transiently accreting systems. It was recently suggested that previously neglected neutron transfer reactions may play a significant role in the nuclear processes. We present results from full nuclear network calculations that now include these reactions and determine their impact on crust composition, crust impurity, heating, and cooling. We find that a large number of neutron transfer reactions indeed occur and impact crust models. In particular, we identify a new type of reaction cycle that brings a pair of nuclei across the nuclear chart into equilibrium via alternating neutron capture and neutron release, interspersed with a neutron transfer. While neutron transfer reactions lead to changes in crust model predictions, and need to be considered in future studies, previous conclusions concerning heating, cooling, and compositional evolution are remarkably robust.

8 pages, 10 figures, accepted for Astrophysical Journal

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Cited by in corpus (6)

• Gravitational radiation from thermal mountains on accreting neutron stars: sources of temperature non-axisymmetry
• Accreting neutron stars: composition of the upper layers of the inner crust
• Improved Nuclear Physics Near $A=61$ Refines Urca Neutrino Luminosities in Accreted Neutron Star Crusts
• Constraining Accreted Neutron Star Crust Shallow Heating with the Inferred Depth of Carbon Ignition in X-ray Superbursts
• Crust composition and the Shallow Heat Source in KS 1731-260
• Layers of electron captures in the crust of accreting neutron stars