Effect of topological defects on "nuclear pasta" observables
Effect of topological defects on "nuclear pasta" observables
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拓扑缺陷对“核意大利面”可观测量的影响
DOI：
10.1103/physrevc.93.065806
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发表时间：
2016
影响因子：
3.1
通讯作者：
Zidu Lin
中科院分区：
文献类型：
--
作者：
A. Schneider;D. Berry;M. Caplan;C. Horowitz;Zidu Lin
背景：核物质的“意大利面”相可能在中子星的结构和演化中发挥重要作用。最近的研究表明，核意大利面具有高电阻率，这可以通过存在长期拓扑缺陷来解释。这些缺陷作为杂质降低了面食的导热性和导电性。
目的：量化拓扑缺陷如何影响核意大利面的输运特性，并使用杂质参数 Q_(imp) 估计这种影响。
方法：将多达 409 600 个核子排列在平行核面食板（完美面食）中的分子动力学模拟与通过拓扑缺陷连接的面食板（不纯面食）的模拟进行对比。通过这些模拟，我们比较了完美意大利面和不纯意大利面的粘度和导热率，以获得由于存在缺陷而产生的有效杂质参数 Q_(imp)。
结果：计算出的完美意大利面和不纯意大利面的粘度和导热率都是各向异性的，沿着垂直于板的方向达到峰值，并在平行于板的方向上达到接近于零的最小值。在我们的 409 600 核子模拟中，连接面食板的拓扑缺陷使热导率和粘度平均降低了约 37%。由于 Q_(imp)∼30 阶的缺陷，我们估计了有效的杂质参数。
结论：核物质面相中的拓扑缺陷具有与晶格中的杂质类似的影响。由缺陷引入的不规则性降低了系统的导热性和导电性以及粘度。这种效应可以通过大的杂质参数 Q_(imp)∼30 来参数化。
Background: The “pasta” phase of nuclear matter may play an important role in the structure and evolution of neutron stars. Recent works suggest nuclear pasta has a high resistivity which could be explained by the presence of long-lived topological defects. The defects act as impurities that decrease thermal and electrical conductivity of the pasta.
Purpose: To quantify how topological defects affect transport properties of nuclear pasta and estimate this effect using an impurity parameter Q_(imp).
Methods: Contrast molecular dynamics simulations of up to 409 600 nucleons arranged in parallel nuclear pasta slabs (perfect pasta) with simulations of pasta slabs connected by topological defects (impure pasta). From these simulations we compare the viscosity and heat conductivity of perfect and impure pasta to obtain an effective impurity parameter Q_(imp) due to the presence of defects.
Results: Both the viscosity and thermal conductivity calculated for both perfect and impure pasta are anisotropic, peaking along directions perpendicular to the slabs and reaching a minimum close to zero parallel to them. In our 409 600 nucleon simulation topological defects connecting slabs of pasta reduce both the thermal conductivity and viscosity on average by about 37%. We estimate an effective impurity parameter due to the defects of order Q_(imp)∼30.
Conclusions: Topological defects in the pasta phase of nuclear matter have an effect similar to impurities in a crystal lattice. The irregularities introduced by the defects reduce the thermal and electrical conductivities and the viscosity of the system. This effect can be parametrized by a large impurity parameter Q_(imp)∼30.