I-Love-⟨c_s^2⟩：中子星平均刚度的近似普适关系
I-Love-$\langle c_s^2 \rangle$: Approximately universal relations for the average neutron star stiffness
AI总结：
本文将中子星中心压强与能量密度之比重新解释为内部平均声速平方⟨c_s^2⟩，并利用后闵可夫斯基展开揭示了其与致密度、转动惯量和潮汐形变率之间准普适关系的物理起源。
摘要：
对中子星的精确观测加深了我们对广义相对论以及高密度核物理性质的认识。将观测与支配这些恒星的微观物理联系起来，有时可以借助近似普适关系。其中一个这样的关系将中心压强与中心能量密度之比和恒星的致密度联系起来，并且已发现该关系对现实状态方程模型的不敏感程度约为10%。在本文中，我们澄清了这一关系中出现的微观量的含义，将其重新解释为恒星内部声速平方的平均值，即⟨c_s^2⟩。随后我们研究了⟨c_s^2⟩-C关系准普适性的物理起源。利用后闵可夫斯基展开，我们发现它与结构方程的牛顿极限有关，也与描述中子星的状态方程相对较硬这一事实有关。同样的后闵可夫斯基方法也被应用于⟨c_s^2⟩、中子星的转动惯量和潮汐形变率之间的关系，并得出了类似的结论。
英文摘要：
The accurate observations of neutron stars have deepened our knowledge of both general relativity and the properties of nuclear physics at large densities. Relating observations to the microphysics that govern these stars can sometimes be aided by approximate universal relations. One such relation connects the ratio of the central pressure to the central energy density and the compactness of the star, and it has been found to be insensitive to realistic models for the equation of state to a $\sim 10\%$ level. In this paper, we clarify the meaning of the microscopic quantity appearing in this relation, which is reinterpreted as the average of the speed of sound squared in the interior of a star, $\langle c_s^2 \rangle\!$. The physical origin of the quasi-universality of the $\langle c_s^2 \rangle - C$ relation is then investigated. Making use of post-Minkowskian expansions, we find it to be linked to the Newtonian limit of the structure equations, as well as to the fact that the equations of state that describe NSs are relatively stiff. The same post-Minkowskian approach is also applied to the relations between $\langle c_s^2 \rangle\!$, the moment of inertia, and the tidal deformability of a neutron star, arriving at similar conclusions.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
