AI 中文总结
该研究通过磁流体动力学模拟，探索日冕零点处振荡重联特性与作为波共振腔的零点性质的联系。通过特定扰动引发周期性重联和波折射，发现重联频率与腔内波频率匹配，且与反射波低频驱动激发频率不同，为相关重联和等离子体条件提供诊断工具。
AI 中文摘要
零点是磁场奇点，磁场强度迅速降至零。在太阳大气中，零点是磁重联和波产生的已知场所，与耀斑等高能现象相关。本研究旨在探索零点处振荡重联的特性与作为波共振腔的零点性质之间的联系。利用PLUTO代码进行了一组分层太阳大气中单个零点的二维和2.5维磁流体动力学模拟。通过单个传播脉冲及其从底部边界的反射以不对称方式撞击零点来扰动每个零点，这导致了周期性重联事件和零点周围的波折射。发现每个零点对重联施加的频率与从单个共振腔产生的波的频率相匹配，这些频率也与反射波返回零点的低频驱动激发的频率不同，后者不在95%置信区间内。因此，激发的周期性重联可被表征为振荡重联。最后，在零点产生的波在整个区域传播，类似于观测到的准周期快速传播波。研究结果显示了振荡重联与日冕零点处产生的高频波列之间的直接联系，在共振腔产生的传播波可为零点处的重联过程和日冕等离子体条件提供诊断工具。
英文摘要
Null points are magnetic field singularities, where the magnetic field strength rapidly drops to zero. In the solar atmosphere, null points are known sites of magnetic reconnection and wave generation and are associated with highly energetic phenomena, such as flares. The aim of this study is to explore the connection between the properties of oscillatory reconnection at null points and the latter's nature as resonant cavities for waves. We perform a set of 2D and 2.5D magnetohydrodynamics simulations of single null points in a stratified solar atmosphere, using the PLUTO code. We perturb each null point through a single propagating pulse and its reflections from the bottom boundary, hitting the null point in an asymmetrical fashion. This leads to both periodic reconnection events and wave refraction around the null point. We find that each null point imposes frequencies on the reconnection matching those of the waves generated from the individual resonant cavity. These frequencies also differ from those excited by the low frequency driver of the reflected waves returning to the null point, the latter lying outside the $95\%$ confidence interval. As such, excited periodic reconnection can be characterised as oscillatory reconnection, i.e. with properties intrinsic to the null points. Finally, the generated waves at the null propagate across the domain, reminiscent of the observed quasi-periodic fast-propagating waves. We provide results showing a direct connection between oscillatory reconnection and the generated high-frequency wavetrains at null points in the solar corona. The propagating waves generated at the resonant cavity, reminiscent of the observed quasi-periodic fast-propagating waves can provide us a diagnostic tool for the reconnection process at the null point and the coronal plasma conditions.
Comments15 pages, 14 figures
