论文标题
太阳耀斑中能量电子加速度,传输和发射的数值建模:连接循环顶部和脚步硬X射线源
Numerical Modeling of Energetic Electron Acceleration, Transport, and Emission in Solar Flares: Connecting Loop-top and Footpoint Hard X-Ray Sources
论文作者
论文摘要
太阳耀斑期间能量电子的加速和运输是太阳能物理学中的出色主题之一。最近的X射线和无线电成像和光谱观察结果提供了对非热电子的分布的诊断,并建议在某些耀斑事件中,电子主要在循环顶部加速,并且可能的经验诱捕和/或散射效应。通过将聚焦的颗粒传输方程与太阳耀斑的磁性水力动力学(MHD)模拟相结合,我们提出了一种自然结合电子加速度和传输的宏观粒子模型。我们的仿真结果表明,诸如湍流螺距散射之类的物理过程可能会对环路上的电子加速和耀斑的运输产生重要影响,并且它们的影响高度取决于能量。依赖空间依赖的湍流散射,并在循环顶部增强,可以使高能量的有效电子加速和大量电子传输到脚尖。我们进一步生成空间分辨的合成硬X射线(HXR)发射图像和光谱,揭示了环形顶部和脚步HXR源。与观察结果相似,我们表明脚步HXR源比Loop-Top HXR源更明亮,更难。我们建议,宏观粒子模型通过将粒子模型与动态发展的太阳能耀斑的MHD模拟相结合,为理解观察到的循环顶部和脚步非热发射源之间的联系提供了新的见解。
The acceleration and transport of energetic electrons during solar flares is one of the outstanding topics in solar physics. Recent X-ray and radio imaging and spectroscopy observations have provided diagnostics of the distribution of nonthermal electrons and suggested that, in certain flare events, electrons are primarily accelerated in the loop-top and likely experience trapping and/or scattering effects. By combining the focused particle transport equation with magnetohydrodynamic (MHD) simulations of solar flares, we present a macroscopic particle model that naturally incorporates electron acceleration and transport. Our simulation results indicate that the physical processes such as turbulent pitch-angle scattering can have important impacts on both electron acceleration in the loop-top and transport in the flare loop, and their influences are highly energy dependent. A spatial-dependent turbulent scattering with enhancement in the loop-top can enable both efficient electron acceleration to high energies and transport of abundant electrons to the footpoints. We further generate spatially resolved synthetic hard X-ray (HXR) emission images and spectra, revealing both the loop-top and footpoint HXR sources. Similar to the observations, we show that the footpoint HXR sources are brighter and harder than the loop-top HXR source. We suggest that the macroscopic particle model provides new insights into understanding the connection between the observed loop-top and footpoint nonthermal emission sources by combining the particle model with dynamically evolving MHD simulations of solar flares.