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arXiv 1902.07032nucl-th
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壳核转换的可压缩液滴模型贝叶斯分析

Bayesian analysis of the crust-core transition with a compressible liquid-drop model

Thomas Carreau, Francesca Gulminelli, Jérôme Margueron

摘要:

在统一的核物质状态方程(EoS)元模型下,对中子星壳核相变进行了定量研究。地壳中的变分方程求解内的可压缩液滴(CLD)的方法,与表面参数一致优化的实验核质量数据的每个EoS集。当EoS参数取自已知的Skyrme或RMF泛函时,这些模型的过渡点被很好地再现。一个独立于模型的概率分布的EoS参数和过渡的密度和压力的贝叶斯分析,其中的先验是由一个不相关的分布参数在目前的经验不确定性,并从中子星物理和从头算建模的约束。我们表明,过渡点的特性在很大程度上是独立的EoS的高密度特性,而从头计算EoS中子和对称物质的约束要大得多。最有影响力的参数确定的过渡点管理的表面性质的极端中子丰富的物质,它是强烈的不受约束。这解释了现有的转变点预测的大分散。只有当表面张力被固定到一个合理的,但有点任意的值,与isovector参数($L_{sym},K_{sym}$和$Q_{sym}$)的强相关性恢复。在这些参数的实验和理论的不确定性,我们估计过渡密度为$n_t= 0.072\pm 0.011$ fm $^{-3}$和过渡压力为$P_t=0.339\pm0.115$ MeV fm $^{-3}$。

英文摘要:

The crust-core phase transition of neutron stars is quantitatively studied within a unified meta-modelling of the nuclear Equation of State (EoS). The variational equations in the crust are solved within a Compressible Liquid Drop (CLD) approach, with surface parameters consistently optimized for each EoS set on experimental nuclear mass data. When EoS parameters are taken from known Skyrme or RMF functionals, the transition point of those models is nicely reproduced. A model-independent probability distribution of EoS parameters and of the transition density and pressure is determined with a Bayesian analysis, where the prior is given by an uncorrelated distribution of parameters within the present empirical uncertainties, and constraints are applied both from neutron star physics and ab-initio modelling. We show that the characteristics of the transition point are largely independent of the high density properties of the EoS, while ab-initio EoS calculations of neutron and symmetric matter are far more constraining. The most influential parameter for the determination of the transition point governs the surface properties of extremely neutron rich matter, and it is strongly unconstrained. This explains the large dispersion of existing predictions of the transition point. Only if the surface tension is fixed to a reasonable but somewhat arbitrary value, strong correlations with isovector parameters ($L_{sym},K_{sym}$ and $Q_{sym}$) are recovered. Within the present experimental and theoretical uncertainties on those parameters, we estimate the transition density as $n_t= 0.072\pm 0.011$ fm$^{-3}$ and the transition pressure as $P_t=0.339\pm0.115$ MeV fm$^{-3}$.

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