Title: Approximate Universal Relations for Neutron Stars and Quark Stars Show Chinese title

Title: 中子星和夸克星的近似通用关系

Abstract: Neutron stars and quark stars are ideal laboratories to study fundamental physics at supra nuclear densities and strong gravitational fields. Astrophysical observables, however, depend strongly on the star's internal structure, which is currently unknown due to uncertainties in the equation of state. Universal relations, however, exist among certain stellar observables that do not depend sensitively on the star's internal structure. One such set of relations is between the star's moment of inertia ($I$), its tidal Love number (Love) and its quadrupole moment ($Q$), the so-called I-Love-Q relations. Similar relations hold among the star's multipole moments, which resemble the well-known black hole no-hair theorems. Universal relations break degeneracies among astrophysical observables, leading to a variety of applications: (i) X-ray measurements of the nuclear matter equation of state, (ii) gravitational wave measurements of the intrinsic spin of inspiraling compact objects, and (iii) gravitational and astrophysical tests of General Relativity that are independent of the equation of state. We here review how the universal relations come about and all the applications that have been devised to date. Show Chinese abstract

Abstract: 中子星和夸克星是研究超核密度和强引力场下基本物理的理想实验室。 然而，天体物理观测量强烈依赖于恒星的内部结构，而由于状态方程的不确定性，目前尚不清楚内部结构。 然而，某些恒星观测量之间存在普遍关系，这些关系对恒星的内部结构不敏感。 其中一组关系是恒星的转动惯量（$I$）、潮汐洛夫数（Love）和四极矩（$Q$）之间的关系，即所谓的I-Love-Q关系。 类似的的关系也存在于恒星的多极矩之间，这些关系类似于众所周知的黑洞无毛定理。 普遍关系消除了天体物理观测量之间的退化，导致了多种应用：(i) X射线测量核物质的状态方程，(ii) 通过引力波测量吸积致密天体的固有自旋，以及(iii) 与状态方程无关的广义相对论的引力和天体物理检验。 我们在此回顾普遍关系是如何产生的，以及到目前为止所设计的所有应用。