论文标题

中子星的新内部模型

New interior model of neutron stars

论文作者

Posada, Camilo, Hladík, Jan, Stuchlík, Zdeněk

论文摘要

托尔曼VII解决方案被某些解决方案视为爱因斯坦方程的少数分析解决方案之一,它大致描述了中子恒星(NSS)的内部。该解决方案的特征是质量$ m $,半径$ r $,并且能量密度随径向坐标$ r $而异。最近,江和Yagi提出了对该溶液的修改,即所谓的修饰Tolman VII(MTVII)溶液,通过向能量密度径向谱的额外术语引入额外的四句话。 MTVII解决方案是爱因斯坦方程的近似解决方案,其中包括一个新的参数$α$,该$α$允许该解决方案与现实NSS的能量密度曲线具有更好的一致性。在这里,我们考虑MTVII解决方案,表明对于参数$α$的某些值和紧凑型$ \ Mathcal {C} $,该解决方案表现出在表面附近的负压区域,从而导致潮汐爱数的负值。为了减轻这些缺点,我们引入了通过求解MTVII能量密度曲线的数值爱因斯坦方程获得的MTVII解决方案的精确版本。作为我们新的精确MTVII(EMTVII)解决方案的应用,我们计算出$ \ Mathcal {C} $的函数的潮汐爱号和潮汐变形性,用于参数$α$的不同值。我们发现,EMTVII解决方案预测了参数$(\ Mathcal {c},α)$的整个允许值的正面潮汐爱数,这与现实NSS的先前结果一致。

The Tolman VII solution is considered by some as one of the few analytical solutions to Einstein's equations, which describes approximately well the interior of neutron stars (NSs). This solution is characterized by the mass $M$, radius $R$, and an energy density that varies quadratically with the radial coordinate $r$. Recently, Jiang and Yagi proposed a modification of this solution, the so-called modified Tolman VII (MTVII) solution, by introducing an additional quartic term to the energy density radial profile. The MTVII solution is an approximate solution to Einstein's equation, which includes a new parameter $α$ that allows the solution to have a better agreement with the energy density profiles for realistic NSs. Here we consider the MTVII solution, showing that for certain values of the parameter $α$ and compactness $\mathcal{C}$ this solution manifests a region of negative pressure near the surface which leads to negative values of the tidal Love number. To alleviate these drawbacks, we introduce an exact version of the MTVII solution obtained by solving numerically Einstein's equations for the MTVII energy density profile. As an application of our new exact MTVII (EMTVII) solution, we calculate the tidal Love number and tidal deformability, as a function of $\mathcal{C}$, for different values of the parameter $α$. We find that the EMTVII solution predicts a positive tidal Love number for the whole range of allowed values of parameters $(\mathcal{C},α)$, in agreement with previous results for realistic NSs.

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