arXiv 2307.040632023-07nucl-thastro-ph.HEnucl-ex

受手征有效场理论计算约束的对称能与中子星性质

Symmetry energy and neutron star properties constrained by chiral effective field theory calculations

Yeunhwan Lim, Achim Schwenk

备注：: Published version, 12 pages, 13 figures
发表信息：: Phys. Rev. C 109, 035801 (2024)
DOI：: 10.1103/PhysRevC.109.035801

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AI总结：

本研究结合手征有效场理论计算、GW170817与NICER观测约束，通过贝叶斯分析和新型能量密度泛函，给出核对称能、中子星半径等性质的置信区间，并探究了相关物理关联与声速约束。

摘要：

我们利用贝叶斯分析研究了核对称能与中子星性质，该分析基于不同手征有效场理论计算给出的约束，采用了可在高密度下产生大幅变化的新型能量密度泛函。高密度约束来自GW170817的观测结果以及NICER（中子星内部成分探测器）的数据。我们特别发现，当纳入我们的物态方程框架时，两项NICER分析得出的对称能与中子星性质后验结果高度相似。基于后验分布，我们给出了对称能、斜率参数，以及中子星内质子丰度、声速和中心密度的结果。此外，我们还探究了中子星半径与中子星内部压强、声速的关联。我们得到的对称能$S_v$、斜率参数$L$以及1.4倍太阳质量中子星半径$R_{1.4}$的95%置信区间分别为：$S_v=(30.6\text{--}33.9)$MeV、$L=(43.7\text{--}70.0)$MeV、$R_{1.4}=(11.6\text{--}13.2)$km。我们对质子丰度的分析表明，更大和/或更重的中子星更有可能通过直接Urca过程快速冷却。在我们的物态方程框架内，中子星最大质量$M_{\rm max}>2.1\rm M_\bigodot$意味着声速需要超出共形极限。

英文摘要：

We investigate the nuclear symmetry energy and neutron star properties using a Bayesian analysis based on constraints from different chiral effective field theory calculations using new energy density functionals that allow for large variations at high densities. Constraints at high densities are included from observations of GW170817 and from NICER. In particular, we show that both NICER analyses lead to very similar posterior results for the symmetry energy and neutron star properties when folded into our equation-of-state framework. Using the posteriors, we provide results for the symmetry energy and the slope parameter, as well as for the proton fraction, the speed of sound, and the central density in neutron stars. Moreover, we explore correlations of neutron star radii with the pressure and the speed of sound in neutron stars. Our 95\% credibility ranges for the symmetry energy $S_v$, the slope parameter $L$, and the radius of a 1.4$\msun$ neutron star, $R_{1.4}$, are $S_v=(30.6\text{--}33.9)$\,MeV, $L=(43.7\text{--}70.0)$\,MeV, and $R_{1.4}=(11.6\text{--}13.2)$\,km. Our analysis for the proton fraction shows that larger and/or heavier neutron stars are more likely to cool rapidly via the direct Urca process. Within our equation-of-state framework a maximum mass of neutron stars $M_{\rm max}>2.1\msun$ indicates that the speed of sound needs to exceed the conformal limit.

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