AI 中文总结
研究太阳耀斑中共轭硬X射线足点不对称性的成因，通过对67个耀斑的103个时间间隔分析，发现足点源在光子通量等方面不对称，磁场和PVEC不对称性与HXR不对称正相关，表明电流相关物理过程影响非热电子产生和沉降。
AI 中文摘要
太阳耀斑中的硬X射线（HXR）发射对非热电子的加速、传输和沉降进行了关键诊断。观测通常显示配对足点之间的HXR光子通量不对称，其物理起源仍存在争议，因为传统的磁镜机制常常无法解释观测到的不对称性。在此，我们对HXR足点区域内的光球磁参数与HXR产生的不对称性之间的关联进行了严格的统计测试。我们分析了由拉马蒂高能太阳光谱成像仪和太阳动力学天文台观测到的67个具有清晰双带形态的M级和X级耀斑中HXR爆发峰值附近的103个时间间隔。我们发现共轭HXR足点源在光子通量、最大强度和大小上是不对称的，但在平均强度上相当对称。较强足点源与较弱足点源的光子通量比与大小比呈强线性相关，与最大强度比呈非线性相关。共轭足点处磁场强度和通量的不对称性与HXR不对称性呈正相关，这与磁镜效应的预测相反。重要的是，无符号光球垂直电流（PVEC）的不对称性与HXR足点不对称性呈强正相关。HXR足点处的PVEC很可能描绘了发生耀斑重联的日冕电流层的足迹。这种紧密联系表明，与电流相关的物理过程，包括重联感应电场和电流驱动的微湍流，正在起作用来调节非热电子的产生和沉降。
英文摘要
Hard X-ray (HXR) emission in solar flares critically diagnoses nonthermal electron acceleration, transport, and precipitation. Observations commonly show asymmetric HXR photon fluxes between paired footpoints, whose physical origin remains debated, as the conventional magnetic mirroring mechanism often fails to explain the observed asymmetry. Here we performed rigorous statistical tests on the association between photospheric magnetic parameters within the HXR footpoint regions and the asymmetry of HXR production. We analyzed 103 time intervals taken from around the peaks of HXR bursts in 67 M- and X-class flares with a clear double-ribbon morphology observed by both the Ramaty High Energy Solar Spectroscopic Imager and the Solar Dynamics Observatory. We found that conjugate HXR footpoint sources are asymmetric in photon fluxes, maximum intensities, and sizes, but rather symmetric in mean intensities. The photon flux ratio of the stronger over weaker footpoint source shows a strong linear correlation with the size ratio and a nonlinear correlation with the maximum intensity ratio. The asymmetry of magnetic field strength and flux at the conjugate footpoints shows a positive correlation with the HXR asymmetry, contrary to what magnetic mirroring effects predict. Importantly, the asymmetry of unsigned photospheric vertical electric current (PVEC) exhibits a strong positive correlation with the HXR footpoint asymmetry. PVEC at HXR footpoints most likely maps the footprints of coronal current layers where flaring reconnections occur. This tight linkage suggests that the electric-current-associated physical processes, including reconnection-induced electric fields and current-driven micro-turbulence, are at work to modulate the production and precipitation of nonthermal electrons.
Comments20 pages, 7 figures, 1 table
