Dense nuclear matter is expected to be anisotropic due to effects such as solidification, superfluidity, strong magnetic fields, hyperons, pion-condensation. Therefore an anisotropic neutron star core seems more realistic than an ideally isotropic one. We model anisotropic neutron stars working in the Krori–Barua (KB) ansatz without preassuming an equation of state. We show that the physics of general KB solutions is encapsulated in the compactness. Imposing physical and stability requirements yields a maximum allowed compactness \(2GM/Rc^2 < 0.71\) for a KB-spacetime. We further input observational data from numerous pulsars and calculate the boundary density. We focus especially on data from the LIGO/Virgo collaboration as well as recent independent measurements of mass and radius of miilisecond pulsars with white dwarf companions by the Neutron Star Interior Composition Explorer (NICER). For these data the KB-spacetime gives the same boundary density which surprisingly equals the nuclear saturation density within the data precision. Since this value designates the boundary of a neutron core, the KB-spacetime applies naturally to neutron stars. For this boundary condition we calculate a maximum mass of 4.1 solar masses.

由于诸如凝固，超流，强磁场，超子，介子凝聚等效应，预计致密核物质将是各向异性的。因此，各向异性中子星核似乎比理想的各向同性星核更为现实。我们在不假定状态方程的情况下，模拟了在Krori–Barua（KB）ansatz中工作的各向异性中子星。我们证明了通用知识库解决方案的物理特性被封装在紧凑性中。施加物理和稳定性要求会产生最大允许的紧密度\（2GM / Rc ^ 2 <0.71 \）一个KB时空。我们进一步输入来自众多脉冲星的观测数据并计算边界密度。我们特别关注LIGO /处女座合作组织提供的数据，以及最近通过中子星内部成分探测器（NICER）对白矮星伴星的毫秒级脉冲星的质量和半径进行独立测量。对于这些数据，KB时空给出相同的边界密度，令人惊讶地等于数据精度内的核饱和密度。由于此值指定中子核的边界，因此KB时空自然适用于中子星。对于此边界条件，我们计算出最大质量为4.1太阳质量。