用关联费米气体模型分析中子星观测
Analysis of Neutron Stars Observations Using a Correlated Fermi Gas Model
摘要：
背景：核对称能是确定中子星（NS）状态方程的基本要素。最近的地面实验限制其值和斜率在核饱和密度，但是，它的值在更高的密度是未知的。假设自由费米气体（FFG）模型的动力学对称能，高密度外推取决于一个单一的参数，密度依赖的潜在的对称能。相关费米气体模型（CFG）是对FFG模型的改进，它包括了核物质中短程、相关、高动量核子的影响。使用CFG模型的动力学对称能量与地面测量的限制，导致一个软得多的密度依赖的潜在的对称能量。目的：检验FFG和CFG模型描述NS观测量的能力，这些观测量在高密度下对对称能直接敏感。具体地说，检查CFG模型的能力，其更软的密度依赖性的潜在的对称性能量，描述两个太阳质量的NS。研究方法：使用贝叶斯分析NS观测值，我们比较的CFG和FFG模型，并检查所得到的参数在NS状态方程和密度依赖的潜在对称能量。结果如下：尽管在对称能的潜在部分的密度依赖性有很大的差异，这两个模型可以描述NS数据和支持两个太阳质量的NS。不同的密度依赖性对NS状态方程只有很小的影响。结论：虽然敏感的对称性能量的高密度值，NS观测值本身是不足以区分的CFG和FFG模型。这表明，由NS观测值的贝叶斯分析得到的NS状态方程是稳健的，并且对用于动力学对称能的精确核模型不敏感。
英文摘要：
Background: The nuclear symmetry energy is a fundamental ingredient in determining the equation of state (EOS) of neutron stars (NS). Recent terrestrial experiments constrain both its value and slope at nuclear saturation density, however, its value at higher densities is unknown. Assuming a Free Fermi-gas (FFG) model for the kinetic symmetry energy, the high-density extrapolation depends on a single parameter, the density dependence of the potential symmetry energy. The Correlated Fermi-gas (CFG) model improves on the FFG model by including the effects of short-range, correlated, high-momentum, nucleons in nuclear matter. Using the CFG model for the kinetic symmetry energy along with constraints from terrestrial measurements leads to a much softer density dependence for the potential symmetry energy. Purpose: Examine the ability of the FFG and CFG models to describe NS observables that are directly sensitive to the symmetry energy at high-density. Specifically, examine the ability of the CFG model, with its softer density dependence of the potential symmetry energy, to describe a two solar-mass NS. Methods: Using a Bayesian analysis of NS observables we compare the CFG and FFG models and examine the resulting parameters in the NS EOS and the density dependence of the potential symmetry energy. Results: Despite the large difference in the density dependence of the potential part of the symmetry energy, both models can describe the NS data and support a two solar-mass NS. The different density dependences has only a small effect on the NS EOS. Conclusions: While sensitive to the high-density values of the symmetry energy, NS observables alone are not enough to distinguish between the CFG and FFG models. This indicates that the NS EOS, obtain from Bayesian analysis of NS observables, is robust and is not sensitive to the exact nuclear model used for the kinetic symmetry energy.
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