Collaborative Research: Effects of the Magnetic Field Shear and Flow Shear on Kinetic Physics in Relativistic Magnetic Reconnection

磁重联是一个基本的等离子体过程，其中磁场线连通性的变化迅速将磁场能量转化为等离子体中带电粒子的加速度。该项目旨在提高我们对天体物理系统中相对论性磁重联的理解。由于对蟹状星云超级耀斑的观测，在过去的五年里，高能天体物理学界对相对论重连产生了浓厚的兴趣。然而，与地球磁层和太阳风的非相对论性对应物相比，高能磁重联及其相关粒子加速的丰富物理学研究仍然较少。这个项目将有助于在太阳物理学和天体物理学社区之间对磁重联的理解，这反过来将有助于对这一基本过程及其潜在应用产生新的见解。这项研究活动将包括在达特茅斯学院培训学生和一名博士后，并通过新墨西哥联盟培训一名暑期实习生。在天体物理系统中，如脉冲星风星云和与伽马射线爆发和黑洞相关的相对论性喷流，磁能密度远远大于等离子体能量密度。在这种强磁化等离子体中，磁重联事件的流出速度可以达到接近光速的值，相对论效应变得重要。在实际系统中，磁重联也经常伴随着有限导向场和流切变。导流场可以降低重联出口速度，而剪切流可以耦合重联与涡旋，影响等离子体输运和能量耗散。因此，研究和确定狭义相对论如何在这些一般条件下影响重联动力学是势在必行的。为了获得粒子加速的自一致图像，并解决破坏磁连通性的耗散尺度物理问题，该项目将采用最先进的粒子单元代码VPIC，并提供相对论状态下无碰撞磁重联的完整动力学描述。这项研究的结果将与许多天体物理学来源相关，并将解决NSF“宇宙之窗：多信使天体物理学时代”大构想的目标。该项目由物理系和促进竞争性研究的既定计划（EPSCoR）联合支持。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Magnetic reconnection is a fundamental plasma process, where a change in the connectivity of magnetic field lines rapidly converts energy of the magnetic field into acceleration of charged particles in the plasma. This project aims to improve our understanding of relativistic magnetic reconnection in astrophysical systems. Prompted by the observation of superflares in the Crab Nebula, over the past five years there has been a surge of interests in relativistic reconnection in the high-energy astrophysics community. However, the rich physics of high energy magnetic reconnection and its associated particle acceleration remain less studied compared to their non-relativistic counterparts in Earth's magnetosphere and solar wind. This project will serve to cross-fertilize understanding of magnetic reconnection between the heliophysics and astrophysics communities, which in turn will help develop new insights into this fundamental process and its potential applications. The research activity will include training of students and a postdoc at Dartmouth College and a summer student intern through the New Mexico Consortium.In astrophysical systems such as pulsar wind nebulae and relativistic jets associated with gamma-ray bursts and black holes, the magnetic energy density is much greater than the plasma energy density. In such strongly magnetized plasmas, outflow speed from magnetic reconnection events can reach values close to the speed of light with relativistic effects becoming important. In a realistic system, magnetic reconnection is also often accompanied by finite guide fields and flow shear. A guide field can reduce the reconnection outflow speed, while a shear flow can couple reconnection with flow vortices to affect plasma transport and energy dissipation. It is thus imperative to study and identify how special relativity can affect the dynamics of reconnection under these general conditions. To obtain a self-consistent picture of particle acceleration and to resolve the dissipation-scale physics that breaks the magnetic connectivity, the project will employ a state-of-the-art particle-in-cell code VPIC and provide a fully kinetic description of collisionless magnetic reconnection in the relativistic regime. The results of this study will be relevant for many astrophysical sources and will address the goals of NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" Big Idea. This project is jointly supported by the Division of Physics and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.