2D Relativistic MHD simulations of the Kruskal-Schwarzschild instability in a relativistic striped wind
2D Relativistic MHD simulations of the Kruskal-Schwarzschild instability in a relativistic striped wind
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相对论性条纹风中克鲁斯卡尔-史瓦西不稳定性的二维相对论 MHD 模拟
DOI：
10.1093/mnras/stx3000
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发表时间：
2017
影响因子：
4.8
通讯作者：
Y. Lyubarsky
中科院分区：
文献类型：
--
作者：
R. Gill;J. Granot;Y. Lyubarsky
我们研究相对论膨胀条纹风中克鲁斯卡-史瓦西不稳定性的线性和非线性发展。这种不稳定性是磁场存在下瑞利-泰勒不稳定性的推广。有人建议在活动星系核、伽马射线爆发和微类星体中发现的强磁化流出中产生自持加速机制。这种不稳定性会导致磁重联，但与稳态 Sweet-Parker 重联相比，耗散率不受当前层小纵横比的限制。我们进行了二维 (2D) 相对论磁流体动力学 (RMHD) 模拟，具有两个冷且高度磁化的 ($1\leq\sigma\leq10^{3}$) 等离子体层，其反平行磁场被一薄层相对论热等离子体分隔开，该等离子体具有由流出加速度引起的局部有效重力。我们的模拟显示了重新连接层中较重的相对论热等离子体如何滴出并允许相反方向的磁场线重新连接。线性状态下不稳定性的增长率与线性稳定性分析的预测相符。我们发现重连区域附近存在湍流，而不是有序的整体流动，湍流速度高达 $\sim0.1$c，很大程度上与模型参数无关。然而，我们发现磁能耗散率要慢得多，相当于流入重联区域 $v_{\rm in}=\beta_{\rm in}c$ 的有效有序体积速度为 $10^{-3}\lesssim\beta_{\rm in}\lesssim 5\times10^{-3}$。发生这种情况是由于热等离子体从当前层缓慢疏散，很大程度上是由于滴落等离子体所经历的开尔文-亥姆霍兹不稳定性。需要 3D RMHD 模拟来进一步研究非线性状态。
We study the linear and non-linear development of the Kruskal-Schwarzchild Instability in a relativisitically expanding striped wind. This instability is the generalization of Rayleigh-Taylor instability in the presence of a magnetic field. It has been suggested to produce a self-sustained acceleration mechanism in strongly magnetized outflows found in active galactic nuclei, gamma-ray bursts, and micro-quasars. The instability leads to magnetic reconnection, but in contrast with steady-state Sweet-Parker reconnection, the dissipation rate is not limited by the current layer's small aspect ratio. We performed two-dimensional (2D) relativistic magneto-hydrodynamic (RMHD) simulations featuring two cold and highly magnetized ($1\leq\sigma\leq10^{3}$) plasma layers with an anti-parallel magnetic field separated by a thin layer of relativistically hot plasma with a local effective gravity induced by the outflow's acceleration. Our simulations show how the heavier relativistically hot plasma in the reconnecting layer drips out and allows oppositely oriented magnetic field lines to reconnect. The instability's growth rate in the linear regime matches the predictions of linear stability analysis. We find turbulence rather than an ordered bulk flow near the reconnection region, with turbulent velocities up to $\sim0.1$c, largely independent of model parameters. However, the magnetic energy dissipation rate is found to be much slower, corresponding to an effective ordered bulk velocity inflow into the reconnection region $v_{\rm in}=\beta_{\rm in}c$, of $10^{-3}\lesssim\beta_{\rm in}\lesssim 5\times10^{-3}$. This occurs due to the slow evacuation of hot plasma from the current layer, largely because of the Kelvin-Helmholtz instability experienced by the dripping plasma. 3D RMHD simulations are needed to further investigate the non-linear regime.
DOI：
10.1088/0067-0049/193/1/6
发表时间：
2011-01
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
K. Beckwith;J. Stone
通讯作者：
K. Beckwith;J. Stone