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

• Applicants: Professor Dr. Jörg Büchner; Dr. Patricio Muñoz
• Subject Area: Astrophysics and Astronomy
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392211132

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.

• DFG Programme: Research Grants
• International Connection: China
• Partner Organisation: National Natural Science Foundation of China
• Cooperation Partner: Professor Siming Liu