Towards Understanding Interstellar Turbulence

虽然湍流是混沌的，但它是可以描述和理解的。湍流是由定义明确的统计定律支配的，可以研究这些定律，然后成功地应用于解决天体物理问题。在这个项目中，亚历山大·拉扎里安博士(威斯康星大学麦迪逊分校)试图通过研究这些定律并将理论与观测进行比较来推进对星际介质(ISM)中磁化湍流的理论理解。这些研究将建立在现有的研究基础上，以及通过拉扎里安博士早期专注于湍流光谱及其对宇宙射线的影响的工作而取得的令人信服的成果。目前的项目是处理ISM湍流中物理条件远离平均水平的小区域的作用(称为“间歇性”)，以及宇宙射线对可压缩湍流的反馈。此外，这项研究将继续开发、测试和应用新的工具，从谱线的速度剖面观测中提取湍流谱。作为这项研究的结果，观测界将拥有新的工具来研究湍流及其各向异性，以及ISM的拓扑结构。螺旋星系的外观、演化和整体性质都受到ISM的强烈影响。反过来，ISM的性质和在其中发生的许多过程(如恒星形成)是由搅动它的磁场湍流决定的。在基本水平上研究磁场湍流对于理解许多过程是至关重要的。仅用“蛮力”数值方法不能自信地理解湍流；计算机模拟的流体运动与天体物理运动的雷诺数有很大的不同。除了将在该项目下进行的研究外，拉扎里安博士还将指导一名研究生，并监督REU和本科生的研究项目。拉扎里安博士还将开展宣传活动，如公开讲座，并将公开提供作为该项目一部分开发的统计工具。

Although turbulence is chaotic, it can be described and understood. Turbulence is governed by well-defined statistical laws that can be studied and then successfully applied to solving astrophysical problems. In this project, Dr. Alexandre Lazarian (University of Wisconsin - Madison) seeks to advance theoretical understanding of magnetized turbulence in the interstellar medium (ISM) by both studying these laws and comparing theory with observations. These studies will build upon the existing research base and the enabling achievements obtained through Dr. Lazarian's earlier work that focused on the spectra of turbulence and its implications for cosmic rays. The present project is to address the role of small regions within the ISM turbulence in which the physical conditions are far from the average (called "intermittency"), as well as the feedback of cosmic rays to the compressible turbulence. In addition, this research will continue developing, testing, and applying new tools for extracting turbulence spectra from observations of the velocity profiles of spectral lines. As the result of this research, the observational community will have new tools to study turbulence and its anisotropy, as well as the topology of the ISM. The appearance, evolution, and overall properties of a spiral galaxy are strongly influenced by its ISM. In turn, the nature of the ISM and many processes taking place within it (such as star-formation) are determined by the magnetic turbulence that stirs it. Examining magnetic turbulence at a fundamental level is vital to understanding many processes. Turbulence cannot be confidently understood using "brute force" numerical approaches only; the fluid motions simulated by computers differ from astrophysical ones by a huge difference in Reynolds numbers. In addition to the research that will be carried out under this project, Dr. Lazarian will mentor a graduate student as well as supervise REU and undergraduate student research projects. Dr. Lazarian will also carry out outreach activities, such as public lectures, and will make the statistical tools developed as a part of this project publicly available.