Instead of parametrizing the pressure-density relation of a neutron star (NS), one can parametrize its macroscopic properties such as mass ($M$), radius ($R$), and dimensionless tidal deformability ($\mathrm{\Lambda }$) to infer the equation of state (EOS) combining electromagnetic and gravitational wave (GW) observations. We present a new method to parametrize $R(M)$ and $\mathrm{\Lambda }(M)$ relations, which approximates the candidate EOSs with accuracy better than 5% for all masses and spans a broad region of the $M-R-\mathrm{\Lambda }$ plane. Using this method we combine the $M-\mathrm{\Lambda }$ measurement from GW170817 and GW190425, and simultaneous $M-R$ measurement of pulsars PSR $\mathrm{J}0030+0451$ and PSR $\mathrm{J}0740+6620$ to place joint constraints on NS properties. At 90% confidence, we infer $R_{1.4}=12.05_{-0.87}^{+0.98}\mathrm{km}$ and ${\mathrm{\Lambda }}_{1.4}=372_{-150}^{+220}$ for a $1.4M_{\odot }$ NS, and $R_{2.08}=12.65_{-1.46}^{+1.36}\mathrm{km}$ for a $2.08M_{\odot }$ NS. Furthermore, we use the inferred values of the maximum mass of a nonrotating NS $M_{\max }=2.52_{-0.29}^{+0.33}{M}_{\odot }$ to investigate the nature of the secondary objects in three potential neutron star–black hole merger (NSBH) systems.

中文翻译：

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用新的状态方程不敏感方法约束中子星特性

除了参数化中子星 (NS) 的压力-密度关系，还可以参数化其宏观性质，例如质量 ($米$）， 半径 （$R$) 和无量纲潮汐变形性 ($\mathrm{\Lambda }$) 来推断结合电磁波和引力波 (GW) 观测的状态方程 (EOS)。我们提出了一种新的参数化方法$R(米)$和$\mathrm{\Lambda }(米)$关系，它以优于 5% 的精度逼近候选 EOS，对于所有质量，并且跨越了广泛的区域$米-R-\mathrm{\Lambda }$飞机。使用这种方法，我们结合$米-\mathrm{\Lambda }$从 GW170817 和 GW190425 测量，同时$米-R$脉冲星 PSR 的测量$\mathrm{Ĵ}0030+0451$和 PSR$\mathrm{Ĵ}0740+6620$在 NS 属性上放置联合约束。在 90% 的置信度下，我们推断$R_{1.4}=12.05_{-0.87}^{+0.98}\mathrm{公里}$和${\mathrm{\Lambda }}_{1.4}=372_{-150}^{+220}$为一个$1.4{米}_{\odot }$NS，和$R_{2.08}=12.65_{-1.46}^{+1.36}\mathrm{公里}$为一个$2.08{米}_{\odot }$NS。此外，我们使用非旋转 NS 的最大质量的推断值${米}_{\mathrm{最大限度}}=2.52_{-0.29}^{+0.33}{米}_{\odot }$研究三个潜在的中子星-黑洞合并（NSBH）系统中次级物体的性质。