标题： 耀发电子加速的动力学调制由于环顶区域的等离子体团-激波相互作用 显示英文标题

标题： Dynamical modulation of solar flare electron acceleration due to plasmoid-shock interactions in the looptop region

摘要： 快模激波可以在重联喷流的前沿形成，并被认为是在太阳耀斑中加速粒子的一个有前景的场所。最近重联的发展表明，大量磁通泡可以在大规模电流层中产生。在这里，我们通过结合磁流体力学模拟与粒子动能模型，研究了当磁通泡间歇性到达激波时，电子在环顶区域加速的动力学调制。当磁通泡与激波相互作用时，环顶区域表现出各种可压缩结构，这些结构调节着高能电子的产生。高能电子群在时间和空间上都迅速变化。5$-$10 keV电子的数量与压缩区面积密切相关，而$>$50 keV电子的数量则与强压缩区的良好相关，但与激波参数的关联仅为中等程度。我们进一步研究了首个磁通泡的影响，它标志着准稳态激波前缘向扭曲和动力学激波的转变。15$-$25 keV的高能电子数量减少了$\sim 20\%$，而25$-$50 keV的高能电子数量几乎减少了40%，但5$-$10 keV电子的数量增加。此外，超过10 keV的电子能量谱随时间变软。我们还发现，当磁通泡穿过激波时，环顶区域可以发展出两个甚至多个不同的源。我们的模拟结果对非热环顶源的解释以及通常观察到的耀斑辐射快速时变现象（包括准周期脉动）具有重要意义。 显示英文摘要

摘要： A fast-mode shock can form in the front of reconnection outflows and has been suggested as a promising site for particle acceleration in solar flares. Recent development of magnetic reconnection has shown that numerous plasmoids can be produced in a large-scale current layer. Here we investigate the dynamical modulation of electron acceleration in the looptop region when plasmoids intermittently arrive at the shock by combining magnetohydrodynamics simulations with a particle kinetic model. As plasmoids interact with the shock, the looptop region exhibits various compressible structures that modulate the production of energetic electrons. The energetic electron population varies rapidly in both time and space. The number of 5$-$10 keV electrons correlates well with the area with compression, while that of $>$50 keV electrons shows good correlation with strong compression area but only moderate correlation with shock parameters. We further examine the impacts of the first plasmoid, which marks the transition from a quasi-steady shock front to a distorted and dynamical shock. The number of energetic electrons is reduced by $\sim 20\%$ at 15$-$25 keV and nearly 40\% for 25$-$50 keV, while the number of 5$-$10 keV electrons increases. In addition, the electron energy spectrum above 10 keV evolves softer with time. We also find double or even multiple distinct sources can develop in the looptop region when the plasmoids move across the shock. Our simulations have strong implications to the interpretation of nonthermal looptop sources, as well as the commonly observed fast temporal variations in flare emissions, including the quasi-periodic pulsations.