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arXiv 1503.01696astro-ph.HEcond-mat.othernucl-th
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中子星壳热导率的量子蒙特卡罗计算

Quantum Monte Carlo calculations of the thermal conductivity of neutron star crusts

Sajad Abbar, Joe Carlson, Huaiyu Duan, Sanjay Reddy

摘要:

本文利用量子蒙特卡罗(QMC)方法计算了单组分离子晶格的静态结构函数$S(q)$,并利用它计算了中子星地壳中高密度固体物质的热导率$κ$。通过与使用标准技术的基础上,在低温下有效的一声子近似(OPA)的热导率的结果进行详细的比较,和多声子谐波近似预计在很宽的温度范围内是有效的,我们评估的温度制度,其中$S(q)$从QMC可以直接用于计算$κ$。我们还比较了QMC的结果,使用经典的Monte Carlo定量评估的量子校正的大小。我们发现,量子效应成为相关的$κ$在温度$T \lesssim 0.3 ~Ω_\mathrm{P}$,其中$Ω_\mathrm{P}$是离子等离子体频率的计算。在$T \simeq 0.1 ~Ω_\mathrm{P}$,量子效应抑制$κ$约$30\%$。与OPA结果的比较表明,$T \lesssim 0.1~ Ω_\mathrm{P}$需要静态结构以外的动力学信息。这些定量比较有助于建立QMC作为一个可行的技术来计算$κ$在中等温度范围内的相关吸积中子星的研究$T=0.1-1~Ω_\mathrm{P}$。这一发现是特别重要的,因为QMC是唯一可行的技术,到目前为止,计算$κ$在多组分系统在低温下。

英文摘要:

We use the quantum Monte Carlo (QMC) techniques to calculate the static structure function $S(q)$ of a one-component ion lattice and use it to calculate the thermal conductivity $κ$ of high-density solid matter expected in the neutron star crust. By making detailed comparisons with the results for the thermal conductivity obtained using standard techniques based on the one-phonon approximation (OPA) valid at low temperature, and the multi-phonon harmonic approximation expected to be valid over a wide range of temperatures, we asses the temperature regime where $S(q)$ from QMC can be used directly to calculate $κ$. We also compare the QMC results to those obtained using classical Monte Carlo to quantitatively asses the magnitude of the quantum corrections. We find that quantum effects became relevant for the calculation of $κ$ at temperature $T \lesssim 0.3 ~Ω_\mathrm{P}$, where $Ω_\mathrm{P}$ is the ion plasma frequency. At $T \simeq 0.1 ~Ω_\mathrm{P}$ the quantum effects suppress $κ$ by about $30\%$. The comparison with the results of the OPA indicates that dynamical information beyond the static structure is needed when $T \lesssim 0.1~ Ω_\mathrm{P}$. These quantitative comparisons help to establish QMC as a viable technique to calculate $κ$ at moderate temperatures in the range $T=0.1-1~Ω_\mathrm{P}$ of relevance to the study of accreting neutron stars. This finding is especially important because QMC is the only viable technique so far for calculating $κ$ in multi-component systems at low-temperatures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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