论文标题
由太阳耀斑合并磁通绳驱动的振荡重新连接和波浪
Oscillatory reconnection and waves driven by merging magnetic flux ropes in solar flares
论文作者
论文摘要
振荡重新连接是一个提出的过程，该过程旨在构成几种太阳和恒星现象的基础，并且很可能在诸如耀斑之类的短暂事件中起重要作用。耀斑排放中的准周期脉动（QPP）可能是振荡重新连接的表现，但潜在的机制仍然不确定。在本文中，我们提出了两个持续磁通磁通绳的2D磁流失动力学（MHD）模拟，其平面磁场经历了振荡性重新连接，其中两个磁通绳合并为单个磁通绳。我们发现，振荡性重新连接可以本质上发生，而没有外部振荡驱动器在通量绳融合过程中，这可能在大规模的冠状环相互作用和碎片电流板中的等离子体合并。此外，我们证明，由于合并后的通量绳的重新连接振荡，在通量绳融化后径向传播非线性波是在通量绳融化的后期产生的。发现这些波的行为几乎与初始的平面磁场无关。据估计，通过合并冠状环和回路电流板中的浆样发射的波将分别具有90 km/s和900 km/s的典型相位速度。在通量绳融合过程中发出的波的性质可能被用作确定合并区域内物理参数的诊断工具。
Oscillatory reconnection is a process that has been suggested to underlie several solar and stellar phenomena, and is likely to play an important role in transient events such as flares. Quasi-periodic pulsations (QPPs) in flare emissions may be a manifestation of oscillatory reconnection, but the underlying mechanisms remain uncertain. In this paper, we present 2D magnetohydrodynamic (MHD) simulations of two current-carrying magnetic flux ropes with an out-of-plane magnetic field undergoing oscillatory reconnection in which the two flux ropes merge into a single flux rope. We find that oscillatory reconnection can occur intrinsically without an external oscillatory driver during flux rope coalescence, which may occur both during large-scale coronal loop interactions and the merging of plasmoids in fragmented current sheets. Furthermore, we demonstrate that radially propagating non-linear waves are produced in the aftermath of flux rope coalescence, due to the post-reconnection oscillations of the merged flux rope. The behaviour of these waves is found to be almost independent of the initial out-of-plane magnetic field. It is estimated that the waves emitted through merging coronal loops and merging plasmoids in loop-top current sheets would have a typical phase speed of 90 km/s and 900 km/s respectively. It is possible that the properties of the waves emitted during flux rope coalescence could be used as a diagnostic tool to determine physical parameters within a coalescing region.
