The Intermittency of ISM Turbulence: What Do the Observations Tell Us?
The Intermittency of ISM Turbulence: What Do the Observations Tell Us?
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ISM 动荡的间歇性：观察结果告诉我们什么？
DOI：
10.1007/978-3-662-44625-6_9
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发表时间：
2015
影响因子：
4.8
通讯作者：
P. Lesaffre
中科院分区：
文献类型：
--
作者：
E. Falgarone;Giorgos Momferratos;P. Lesaffre
星际介质是高度湍流的，但这种介质，一种部分电离的等离子体，也是多相的，可压缩的和磁化的，因此其湍流的复杂性超出了理论的掌握。湍流与引力一起在星星形成过程中扮演着关键角色，预计它的耗散也是一个关键过程。湍流耗散的一个基本性质是其时空不变性，主要在流体动力学湍流中研究。在概述了我们基于实验室实验、理论和数值模拟的有限知识之后，本章收集了一组观测结果，这些观测结果现在由于分子光谱学和偏振测量的新能力而成为可能，这些观测结果可以被视为磁化湍流星际介质中的非线性特征。它包括强大的星际速度场的统计方法，在非常小的尺度上检测大的速度剪切，以及间歇性耗散的化学和辐射诊断。磁化耗散爆发的模型，无论是在相干涡或低速C-冲击的形式也提出和面临的意见，以及磁流体动力学（MHD）和非理想湍流的频谱模拟中最强烈的耗散区域的结果。
The interstellar medium is highly turbulent, but this medium, a partially ionized plasma, is also multi-phase, compressible and magnetized, hence the complexity of its turbulence extends beyond theoretical grasp. Turbulence being with gravity a key player in the star formation process, it is anticipated that its dissipation is a key process too. A fundamental property of turbulent dissipation is its space-time intermittency, studied mostly in hydrodynamical turbulence. After an overview of our limited knowledge of intermittency based on laboratory experiments, theory and numerical simulations, this chapter gathers the set of observations, now made possible by the new capabilities of molecular spectroscopy and polarimetry, that may be seen as signatures of intermittency in the magnetized turbulent interstellar medium. It includes powerful statistical approaches of the interstellar velocity field, the detection of large velocity-shears at very small scales, and chemical and radiative diagnostics of intermittent dissipation. Models of magnetized dissipation bursts, either in the form of coherent vortices or low velocity C-shocks are also presented and confronted to observations, as well as results on the regions of most intense dissipation in spectral simulations of magneto-hydrodynamical (MHD) and non-ideal turbulence.