通过纳入直接Urca冷却扩展对中子星物质的多信使约束

中文摘要 AI 辅助

极端密度下强相互作用物质的性质和行为不仅可以通过地面实验或理论考虑来确定，而且对中子星（NSs）和双中子星系统的天体物理观测在获取补充信息方面也变得越来越重要。鉴于这些发现，我们进行了一项贝叶斯研究，通过纳入直接Urca（dUrca）过程的约束来推断中子星状态方程（EoS），从而在传统使用的宏观可观测量的基础上，额外包含物质组成的信息。我们在\textsc{jester}框架中实现了$\beta$平衡和电荷中性的自洽处理，包括质子份额的计算以及存在电子和缪子时核子dUrca的起始条件。我们结合了来自手征有效场论、中子星质量、半径和潮汐形变度的天体物理测量，以及快速和缓慢冷却中子星的观测约束。dUrca约束似乎倾向于更硬的EoS，但在当前阶段，一旦我们纳入其他核和天体物理约束，它对中子星宏观性质的影响较小。相反，dUrca信息提供了对标准质量中子星组成的约束，倾向于星内更高的质子份额，这说明了冷却观测所携带的补充信息。我们的结果展示了将组成敏感的观测量纳入多信使推断的潜力，并为使用微观动机的EoS模型更全面地处理dUrca约束迈出了一步。

英文摘要

The properties and behavior of strongly interacting matter at extreme densities can not only be determined through terrestrial experiments or through theoretical considerations, but also astrophysical observations of neutron stars (NSs) and binary neutron star systems become increasingly important to obtain complementary information. In light of these findings, we perform a Bayesian study inferring the NS equation of state (EoS) by incorporating constraints from the direct Urca (dUrca) process, thereby including information on matter composition in addition to traditionally used macroscopic observables. We implement a self-consistent treatment of $β$-equilibrium and charge neutrality in the \textsc{jester} framework, including the calculation of the proton fraction and the onset of nucleonic dUrca in the presence of electrons and muons. We combine constraints from chiral effective field theory, astrophysical measurements of NS masses, radii, and tidal deformabilities, and observations of rapidly and slowly cooling neutron stars. The dUrca constraint seems to be in favor of stiffer EoSs, but --at the current stage-- has only a minor impact on macroscopic NS properties once we include other nuclear and astrophysical constraints. In contrast, the dUrca information provides a constraint on the composition of canonical-mass NSs favoring a higher proton fraction inside the star, illustrating the complementary information carried by cooling observations. Our results demonstrate the potential of incorporating composition-sensitive observables into multimessenger inference and provide a step toward a more comprehensive treatment of dUrca constraints with microscopically motivated EoS models.

发表机构

• Universität Potsdam（波茨坦大学）
• National Research and Innovation Agency (BRIN)（国家研究与创新署）
• Utrecht University（乌得勒支大学）
• Nikhef（尼赫夫）
• Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））

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