Particle Acceleration During Collisionless Magnetic Reconnection

这项研究将探索太阳耀斑和类似天体物理事件中高能带电粒子加速的机制。磁能的爆炸性释放是自然界许多重要现象的驱动力，包括太阳和遥远天体上的耀斑，地球空间环境中的风暴，以及实验室聚变实验的中断。太阳大气中的能量释放是空间天气的驱动因素，这会对我们的天基卫星通信系统产生负面影响，并威胁到宇航员在太空中的安全。磁能的释放是通过一个称为磁重联的过程进行的，在这个过程中，指向相反方向的磁场会湮灭。虽然在理解快速释放磁能的机制方面已经取得了很大的进展，但负责将带电粒子加速到高能的机制仍然只有部分了解，是本研究的重点。通过这样做，它将为美国国家科学基金会“宇宙之窗：多信使天体物理学时代”的宏大构想的目标做出贡献。太阳耀斑观测和地球磁尾的现场观测表明，释放的大部分磁能以高能离子和电子的形式出现。测量的粒子分布采用扩展的幂定律的形式，其中在给定能量下的粒子数量与该能量的反幂成正比。磁重联的模拟工作还没有成功地产生这样的幂定律粒子分布。一种新的计算模型正在开发中，用于探索大空间尺度区域中的粒子加速，这些区域表征了自然界中的重新连接系统。新的模型首次揭示了观测中所看到的高能粒子分布，并将用于建立基本的粒子加速机制以及电子、质子和正电荷离子之间的能量分配。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This study will explore the mechanisms responsible for acceleration of high energy charged particles in solar flares and similar astrophysical events. The explosive release of magnetic energy is the driver of many important phenomena in nature, including flares on the sun and remote astrophysical objects, storms in the Earth's space environment and disruptions in laboratory fusion experiments. Energy release in the solar atmosphere is the driver of space weather, which can negatively impact our space-based satellite communication systems and threaten the safety of astronauts in space. The release of magnetic energy takes place through a process called magnetic reconnection in which magnetic fields pointing in opposite directions annihilate. While great progress has been made in understanding the mechanisms for the fast release of magnetic energy, the mechanisms responsible for the acceleration of charged particles to high energy remain only partially understood and are the focus of this study. In doing so, it will contribute to the goals of NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" Big Idea. Solar flare observations and in situ observations in the Earth’s magnetotail suggest that a large fraction of the magnetic energy released appears in the form of energetic ions and electrons. The measured particle distributions take the form of extended powerlaws in which the number of particles at a given energy is proportional to an inverse power of that energy. Modeling efforts of magnetic reconnection have not been successful in producing such powerlaw particle distributions. A new computational model is being developed for exploring particle acceleration in the regions of large spatial scale that characterize reconnecting systems in nature. The new model is for the first time revealing the high energy particle distributions as seen in observations and will be used to establish the underlying particle acceleration mechanisms and the partitioning of energy between electrons, protons and positively charged ions.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.