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arXiv 2211.04553astro-ph.HEphysics.plasm-ph
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相对论无碰撞等离子体团介导重联中的有效电阻率

Effective resistivity in relativistic collisionless plasmoid-mediated reconnection

Sebastiaan Selvi, Oliver Porth, Bart Ripperda, Fabio Bacchini, Lorenzo Sironi, Rony Keppens

AI总结:

本文通过PIC模拟研究相对论无碰撞等离子体团介导重联,发现非理想电场由非回旋热压力梯度驱动,并提出局域有效电阻率模型,为重联高能辐射的全局建模提供物理基础。

摘要:

磁重联可以通过在致密天体周围高度磁化区域产生非热能量分布,从而驱动壮观的高能天体物理现象。通过二维全动力学粒子网格(PIC)模拟,我们研究了有无引导场情况下磁主导对等离子体中相对论无碰撞等离子体团介导的重联。在X点,发散流导致非对角热压力张量,粒子的有限驻留时间产生了局域化的无碰撞有效电阻率。在此,我们首次针对完全发展的等离子体团链中的相对论重联,利用基于PIC模拟的统计分析,通过完整的欧姆定律识别了驱动非理想电场的机制。我们表明,非理想电场主要由非回旋热压力梯度驱动。我们提出了一个受动力学物理启发的非均匀有效电阻率模型,该模型在全局尺度上可忽略,仅在X点局域变得显著,能够捕捉无碰撞重联的特性,旨在非理想磁流体动力学描述中模拟其要点。该有效电阻率模型为设计基于物理的重联驱动高能辐射全局模型提供了可行途径。

英文摘要:

Magnetic reconnection can power spectacular high-energy astrophysical phenomena by producing non-thermal energy distributions in highly magnetized regions around compact objects. By means of two-dimensional fully kinetic particle-in-cell (PIC) simulations we investigate relativistic collisionless plasmoid-mediated reconnection in magnetically dominated pair plasmas with and without guide field. In X-points, where diverging flows result in a non-diagonal thermal pressure tensor, a finite residence time for particles gives rise to a localized collisionless effective resistivity. Here, for the first time for relativistic reconnection in a fully developed plasmoid chain we identify the mechanisms driving the non-ideal electric field using a full Ohm's law by means of a statistical analysis based on our PIC simulations. We show that the non-ideal electric field is predominantly driven by gradients of nongyrotropic thermal pressures. We propose a kinetic physics motivated non-uniform effective resistivity model, which is negligible on global scales and becomes significant only locally in X-points, that captures the properties of collisionless reconnection with the aim of mimicking its essentials in non-ideal magnetohydrodynamic descriptions. This effective resistivity model provides a viable opportunity to design physically grounded global models for reconnection-powered high-energy emission.

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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