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arXiv 2008.11338nucl-thastro-ph.HEastro-ph.SRnucl-ex
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核对称能的曲率-斜率相关及其对正则中子星壳核转换、半径和潮汐形变的影响

Curvature-slope correlation of nuclear symmetry energy and its imprints on the crust-core transition, radius and tidal deformability of canonical neutron stars

Bao-An Li, Macon Magno

摘要:

背景:核对称能$E_{sym}(ρ)$编码了使核系统更富中子所需的能量信息。虽然它在核物质饱和密度$ρ_0$处的斜率参数L已经被最近的天体物理观测和地球核实验相对较好地约束,但它表征$2ρ_0$周围$E_{sym}(ρ)$的曲率$K_{\rm{sym}}$仍然很大程度上不受约束。在文献中,使用各种核理论和相互作用对$E_{sym}(ρ)$进行了超过520次计算,预测了几种显著不同的$K_{\rm{sym}}-L$相关性。目的:如果可以牢固地建立$E_{sym}(ρ)$的唯一的$K_{\rm{sym}}-L$相关性,则将使我们能够使用对其斜率参数L的可用约束来逐渐更好地约束$E_{sym}(ρ)$的高密度行为。我们研究了不同的$K_{\rm{sym}}-L$相关性是否会影响中子星的可观测性以及影响程度。方法:利用具有三个代表性$K_{\rm{sym}}-L$关联函数的核状态方程元模型,生成了中子星的多个状态方程。然后,我们研究的$K_{\rm{sym}}-L$相关的壳核过渡密度和压力,以及半径和潮汐变形的正则中子星的影响。结果:$K_{\rm{sym}}-L$相关性对壳核转换密度和压力均有显著影响。它对正则中子星的半径和潮汐形变也有很强的影响,特别是在小L值的情况下。来自LIGO/VIRGO和NICER的可用数据为斜率L设置了一些有用的限制,但不能区分所考虑的三种代表性的$K_{\rm{sym}}-L$相关性。

英文摘要:

Background: The nuclear symmetry energy $E_{sym}(ρ)$ encodes information about the energy necessary to make nuclear systems more neutron-rich. While its slope parameter L at the saturation density $ρ_0$ of nuclear matter has been relatively well constrained by recent astrophysical observations and terrestrial nuclear experiments, its curvature $K_{\rm{sym}}$ characterizing the $E_{sym}(ρ)$ around $2ρ_0$ remains largely unconstrained. Over 520 calculations for $E_{sym}(ρ)$ using various nuclear theories and interactions in the literature have predicted several significantly different $K_{\rm{sym}}-L$ correlations. Purpose: If a unique $K_{\rm{sym}}-L$ correlation of $E_{sym}(ρ)$ can be firmly established, it will enable us to progressively better constrain the high-density behavior of $E_{sym}(ρ)$ using the available constraints on its slope parameter L. We investigate if and by how much the different $K_{\rm{sym}}-L$ correlations may affect neutron star observables. Method: A meta-model of nuclear Equation of States (EOSs) with three representative $K_{\rm{sym}}-L$ correlation functions is used to generate multiple EOSs for neutron stars. We then examine effects of the $K_{\rm{sym}}-L$ correlation on the crust-core transition density and pressure as well as the radius and tidal deformation of canonical neutron stars. Results:The $K_{\rm{sym}}-L$ correlation affects significantly both the crust-core transition density and pressure. It also has strong imprints on the radius and tidal deformability of canonical neutron stars especially at small L values. The available data from LIGO/VIRGO and NICER set some useful limits for the slope L but can not distinguish the three representative $K_{\rm{sym}}-L$ correlations considered.

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