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

磁重联是最有效地将磁能转化为等离子体动能、热量和粒子加速到高能的基本过程。据推测，它发生在所有磁化的天体物理等离子体中，包括星冕。太阳耀斑中的重联可以通过电磁辐射远程探测。高能电子携带着太阳耀斑期间释放的相当大一部分能量，将其中一部分转化为可观察到的电磁辐射。对于通过电磁辐射进行重联的远程探测，了解磁重联对电子的加速对天体物理学具有重要意义。另一方面，由高能电子引起的辐射，如第三类太阳射电爆发(SRB)，打开了一条关于迄今尚未被很好理解的快速天体物理重新连接过程的信息渠道。为此，人们必须了解由磁重联加速的电子产生相干辐射的物理学原理。与标准的波波等离子体发射不同，电子回旋脉泽(ECM)不稳定性引起的波粒过程是另一种可能的机制，但现有理论存在缺陷。为了克服现有ECM理论的不足，我们计划通过全动力学粒子单元(PIC)代码模拟，通过自产生的不稳定的Alfvenic等离子体波，验证磁重联及其电子加速与可观测无线电波产生的直接联系的新情景。我们的目标是从物理上理解动磁重联的基本过程，包括它与自产生的小尺度湍流的相互作用。我们的数值模拟结果将与简化假设下的理论预测相验证。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明安图超宽带射电日光仪(MUSER)的太阳射电观测进行比较。电子加速的研究还将有助于为未来的空间任务准备无线电和X射线观测，如欧洲太阳轨道器和中国先进的空间太阳天文台(ASO-S)。因此，我们希望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向前迈出重要的一步，方法是结合太阳耀斑的远程观测进行运动学和数值模拟。

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.