MAGNETIC FIELD AMPLIFICATION AND EVOLUTION IN TURBULENT COLLISIONLESS MAGNETOHYDRODYNAMICS: AN APPLICATION TO THE INTRACLUSTER MEDIUM
MAGNETIC FIELD AMPLIFICATION AND EVOLUTION IN TURBULENT COLLISIONLESS MAGNETOHYDRODYNAMICS: AN APPLICATION TO THE INTRACLUSTER MEDIUM
复制标题
湍流无碰撞磁流体动力学中的磁场放大和演化：簇内介质的应用
DOI：
10.1088/0004-637x/781/2/84
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
M. S. Nakwacki
中科院分区：
文献类型：
--
作者：
R. Santos;E. M. D. G. D. Pino;Grzegorz Kowal;D. Falceta;D. Falceta;A. Lazarian;M. S. Nakwacki;M. S. Nakwacki
团内介质（ICM）中磁场的放大归因于湍流发电机（TD）作用，这通常是在碰撞-MHD框架中推导出来的。然而，这种假设是不合理的先验，因为在ICM的离子碰撞之间的平均自由程的动力学尺度的顺序，因此需要一个无碰撞的MHD描述。本研究使用各向异性的等离子体压力，使等离子体的参数空间内发生无碰撞不稳定性。在该模型中，压力各向异性的松弛项模拟了反射镜和消防水龙带不稳定性的反馈，与经验研究一致。针对湍流ICM的模拟，我们对不同的MF强度初始值和不同的压力各向异性弛豫率进行了三维强迫跨音速湍流的数值模拟。我们发现，在对应于ICM条件的高β等离子体区，快的各向异性弛豫速率给出了与碰撞MHD模型相似的结果，就湍流的统计性质而言。此外，TD放大种子MF被发现是类似的碰撞MHD模型。不采用各向异性弛豫的模拟偏离显着的碰撞MHD的结果，并显示更多的权力在小尺度波动的密度和速度的不稳定性的作用的结果。对于这些模拟，MF中的大规模波动大多被抑制，并且TD在放大种子MF中失败。
The amplification of magnetic fields (MFs) in the intracluster medium (ICM) is attributed to turbulent dynamo (TD) action, which is generally derived in the collisional-MHD framework. However, this assumption is poorly justified a priori, since in the ICM the ion mean free path between collisions is of the order of the dynamical scales, thus requiring a collisionless MHD description. The present study uses an anisotropic plasma pressure that brings the plasma within a parametric space where collisionless instabilities take place. In this model, a relaxation term of the pressure anisotropy simulates the feedback of the mirror and firehose instabilities, in consistency with empirical studies. Our three-dimensional numerical simulations of forced transonic turbulence, aiming the modeling of the turbulent ICM, were performed for different initial values of the MF intensity and different relaxation rates of the pressure anisotropy. We found that in the high-β plasma regime corresponding to the ICM conditions, a fast anisotropy relaxation rate gives results that are similar to the collisional-MHD model, as far as the statistical properties of the turbulence are concerned. Also, the TD amplification of seed MFs was found to be similar to the collisional-MHD model. The simulations that do not employ the anisotropy relaxation deviate significantly from the collisional-MHD results and show more power at the small-scale fluctuations of both density and velocity as a result of the action of the instabilities. For these simulations, the large-scale fluctuations in the MF are mostly suppressed and the TD fails in amplifying seed MFs.
银河管理 à trois：模拟碰撞星系中的磁场
DOI：
10.1111/j.1365-2966.2011.18932.x
发表时间：
2011
影响因子：
4.8
作者：
Kotarba;Johansson;Donnert;Stasyszyn
通讯作者：
Stasyszyn