Neutron stars provide a cosmic laboratory to study the nature of dark matter particles and their interactions. Dark matter can be captured by neutron stars via scattering, where kinetic energy is transferred to the star. This can have a number of observational consequences, such as the heating of old neutron stars to infra-red temperatures. Previous treatments of the capture process have employed various approximation or simplifications. We present here an improved treatment of dark matter capture, valid for a wide dark matter mass range, that correctly incorporates all relevant physical effects. These include gravitational focusing, a fully relativistic scattering treatment, Pauli blocking, neutron star opacity and multi-scattering effects. We provide general expressions that enable the exact capture rate to be calculated numerically, and derive simplified expressions that are valid for particular interaction types or mass regimes and that greatly increase the computational efficiency. Our formalism is applicable to the scattering of dark matter from any neutron star constituents, or to the capture of dark matter in other compact objects.

中文翻译：

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中子星暗物质捕获的改进处理

中子星为研究暗物质粒子的性质及其相互作用提供了一个宇宙实验室。暗物质可以通过散射被中子星捕获，其中动能被转移到恒星。这可能会产生许多观测结果，例如将旧中子星加热到红外温度。捕获过程的先前处理采用了各种近似或简化。我们在此介绍了一种改进的暗物质捕获处理方法，适用于较宽的暗物质质量范围，并正确地结合了所有相关的物理效应。这些包括引力聚焦、完全相对论散射处理、泡利阻挡、中子星不透明和多重散射效应。我们提供了通用表达式，可以通过数值计算准确的捕获率，并推导出对特定相互作用类型或质量体系有效的简化表达式，这大大提高了计算效率。我们的形式主义适用于从任何中子星成分中散射暗物质，或捕获其他致密物体中的暗物质。