Magnetic field amplification by SN-driven interstellar turbulence
Magnetic field amplification by SN-driven interstellar turbulence
复制标题
SN驱动的星际湍流的磁场放大
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
D. Elstner
中科院分区：
文献类型：
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作者：
O. Gressel;U. Ziegler;D. Elstner
众所周知，超新星是星际介质中驱动湍流的主要能源。然而，它们对螺旋星系磁场放大的影响仍然知之甚少。基于非相关系综方法的分析模型预测，任何创建的字段将被驱逐出磁盘之前，一个显着的放大可以发生。通过对超新星驱动湍流的直接模拟，我们证明了情况并非如此。占垂直分层和银河系的差异旋转，我们发现一个指数放大的平均场的时间尺度为1亿年。我们强调旋转的重要性，在产生螺旋度表明，一个类似的机制的基础上笛卡尔剪切不会导致持续放大的平均磁场。
Supernovae are known to be the dominant energy source for driving turbulence in the interstellar medium. Yet, their effect on magnetic field amplification in spiral galaxies is still poorly understood. Analytical models based on the uncorrelated-ensemble approach predicted that any created field will be expelled from the disk before a significant amplification can occur. By means of direct simulations of supernova-driven turbulence, we demonstrate that this is not the case. Accounting for vertical stratification and galactic differential rotation, we find an exponential amplification of the mean field on timescales of 100 Myr. We highlight the importance of rotation in the generation of helicity by showing that a similar mechanism based on Cartesian shear does not lead to a sustained amplification of the mean magnetic field.