同步涨落梯度揭密磁流体动力学湍流三维磁场结构

磁流体动力学(MHD)湍流普遍存在于天体物理中，对关键的天体物理活动影响深远，如恒星的形成、吸积盘中角动量的转移、湍流磁重联等。鉴于此，本项目借助同步辐射统计涨落的理论框架，基于目前对MHD湍流理论的理解，拟将数值模拟与观测研究相结合，开发以同步辐射梯度为核心的新技术，致力于MHD湍流马赫数的测量、磁化等离子体湍流模的识别及3D磁场的测绘。本项目将①引进并应用同步梯度技术，构建梯度统计量与马赫数之间的关系，定量测量MHD湍流关键参数；②依据MHD湍流的可压缩性追踪湍流磁场方向，搭建偏振结构函数的级数展开与各分模的关联，实现梯度统计识别模式技术的突破；③发挥梯度技术的协同作用，开辟同步自吸收效应测绘3D磁场结构的新途径。旨在以实现重构银河及近邻星系磁场3D结构及测绘星际介质3D磁化强度为主要科学目标，以期为MHD湍流在天体物理中的应用研究提供新视角，促使MHD湍流基本理论得到发展与完善。

Magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysics and has a profound influence on key astrophysical processes, such as star formation, angular momentum transfer in accretion disks, propagation and acceleration of cosmic rays, and turbulent magnetic reconnection. On the framework of synchrotron radiation statistical fluctuation theory, we are committed to the measuring of Mach numbers of MHD turbulence, identifying of magnetized plasma turbulence modes as well as surveying and mapping of 3D magnetic field on the basis of the modern understanding of MHD turbulence theory by proposing synchrotron-emission-gradient-oriented techniques combining numerical simulation with observational data. This project will (1) introduce the application of synchrotron gradient technique, construct a solid relationship between gradient statistics and Mach numbers, and measure key parameters of MHD turbulence quantitatively; (2) explore the co-relationship between the series expansion of the polarization structure function and three (Alfven, slow and fast) modes by tracing turbulent magnetic field direction according to the compressibility of MHD turbulence, and make a technique breakthrough in terms of gradient statistics to identify modes; (3) combine the synergistic effect of Faraday and Zeeman gradients with the synchrotron emission gradients, and open up a new way of mapping 3D magnetic field structure by means of synchrotron self-absorption effect. The project aims to reconstruct the 3D magnetic field structure of the Milky Way and its neighboring galaxies and map the 3D magnetization intensity of the interstellar medium, which will shed a new light on the studies related to MHD turbulence in the field of astrophysics and make a contribution to the development and improvement of the theory of MHD turbulence.