Probing electron acceleration by fast kinetic guide-field magnetic reconnection using coherent solar radio emissions

使用相干太阳射电发射通过快速动导场磁重联探测电子加速

• 批准号: 392211132
• 负责人: Professor Dr. Jörg Büchner
• 金额: --
• 依托单位: Max-Planck-Institut für Sonnensystemforschung (MPS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/392211132?language=en
• 关键词: Probing; electron; acceleration; fast; kinetic

Magnetic reconnection is a fundamental process of the most efficient transfer of magnetic into plasma kinetic energy, heat and acceleration of particles to high energies. It presumably takes place in all magnetized astrophysical plasmas including stellar coronae. Reconnection in solar flares can be probed remotely by electromagnetic radiation. Energetic electrons carry a substantial portion of the energy released during solar flares transferring part of it to observable electromagnetic radiation. For the remote detection of reconnection via electromagnetic radiation the understanding of the electron acceleration by magnetic reconnection is of major interest for astrophysics in general. On the other hand radiation caused by energetic electrons, like type-III solar radio bursts (SRBs), opens a channel of information about the so far not well understood fast astrophysical reconnection processes. For this purpose one has to understand the physics of generation of coherent radiation by electrons accelerated by magnetic reconnection. Different from the standard wave-wave plasma emission, the wave-particle process due to an electron cyclotron maser (ECM) instability is another probable mechanism that has, however, shortcomings in the existing theory. To remove the deficiencies of the existing ECM theories we plan to verify a novel scenario of a direct link of magnetic reconnection and its electron acceleration to the generation of observable radio waves, via self-generated unstable Alfvenic plasma waves, by means of fully-kinetic Particle-in-Cell (PIC)-code simulations. We aim at a physical understanding of the underlying processes of kinetic magnetic reconnection including its interaction with the self-generated small-scale turbulence. Our numerical simulation results will be validated with theoretical predictions for simplified assumptions. We then are going to compare our results with solar radio observations by the European LOFAR, the international ALMA telescopes as well as by the Chinese Solar Imaging with the Mingantu Ultrawide SpEctral Radioheliograph (MUSER). The study of electron acceleration will also help to prepare radio and X-ray observations of future space missions like the European Solar Orbiter and the Chinese Advanced Space-based Solar Observatory (ASO-S). Thus, we want to make a significant step forward towards a better understanding of magnetic reconnection, electron acceleration and the generation of coherent radio emissions by kineticnumerical simulations in combination with remote observations of solar flares.

磁重联是将磁能最有效地转化为等离子体动能、热量以及将粒子加速到高能的基本过程。它可能发生在包括恒星日冕在内的所有磁化天体物理等离子体中。太阳耀斑的重新连接可以通过电磁辐射进行远程探测。高能电子携带着太阳耀斑期间释放的大部分能量，并将部分能量转移为可观测的电磁辐射。对于通过电磁辐射远程检测重联来说，对磁重联电子加速的理解通常是天体物理学的主要兴趣。另一方面，由高能电子引起的辐射，如III型太阳射电爆发（SRB），打开了一条有关迄今为止尚未很好理解的快速天体物理重联过程的信息通道。为此，我们必须了解由磁重联加速的电子产生相干辐射的物理原理。与标准的波-波等离子体发射不同，由于电子回旋微波激射器（ECM）不稳定性导致的波-粒子过程是另一种可能的机制，但现有理论存在缺陷。为了消除现有 ECM 理论的缺陷，我们计划验证一种新的场景，即磁重联及其电子加速与可观测无线电波的生成的直接联系，通过自生的不稳定阿尔芬尼等离子体波，通过全动力学细胞内粒子 (PIC) 代码模拟。我们的目标是对动磁重联的基本过程进行物理理解，包括其与自生小尺度湍流的相互作用。我们的数值模拟结果将通过简化假设的理论预测进行验证。然后，我们将把我们的结果与欧洲 LOFAR、国际 ALMA 望远镜以及中国太阳成像与 Mingantu 超宽谱射电日光仪 (MUSER) 的太阳射电观测结果进行比较。电子加速的研究还将有助于为欧洲太阳轨道飞行器和中国先进天基太阳观测站（ASO-S）等未来太空任务的无线电和X射线观测做好准备。因此，我们希望通过动力学数值模拟结合太阳耀斑的远程观测，在更好地理解磁重联、电子加速和相干射电发射的产生方面迈出重要一步。