Regularized imaging spectroscopy was introduced for the construction of electron flux images at different energies from count visibilities recorded by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). In this work we seek to extend this approach to data from the Spectrometer/Telescope for Imaging X-rays (STIX) on-board the Solar Orbiter mission. Our aims are to demonstrate the feasibility of regularized imaging spectroscopy as a method for analysis of STIX data, and also to show how such analysis can lead to insights into the physical processes affecting the nonthermal electrons responsible for the hard X-ray emission observed by STIX. STIX records imaging data in an intrinsically different manner from RHESSI. Rather than sweeping the angular frequency plane in a set of concentric circles (one circle per detector), STIX uses $30$ collimators, each corresponding to a specific angular frequency. In this paper we derive an appropriate modification of the previous computational approach for the analysis of the visibilities observed by STIX. This approach also allows for the observed count data to be placed into non-uniformly-spaced energy bins. We show that the regularized imaging spectroscopy approach is not only feasible for analysis of the visibilities observed by STIX, but also more reliable. Application of the regularized imaging spectroscopy technique to several well-observed flares reveals details of the variation of the electron flux spectrum throughout the flare sources. We conclude that the visibility-based regularized imaging spectroscopy approach is well-suited to analysis of STIX data. We also use STIX electron flux spectral images to track, for the first time, the behavior of the accelerated electrons during their path from the acceleration site in the solar corona toward the chromosphere

翻译：正则化成像光谱技术最初被用于从Reuven Ramaty高能太阳光谱成像仪（RHESSI）记录的能量计数可见度数据中重构不同能量下的电子通量图像。本研究旨在将该方法拓展至太阳轨道器任务搭载的X射线成像光谱望远镜（STIX）数据。我们的目标一是证明正则化成像光谱法分析STIX数据的可行性，二是展示此类分析如何揭示影响非热电子（即产生STIX观测到的硬X射线发射的电子）的物理过程。与RHESSI本质不同，STIX以独特方式记录成像数据：它不采用同心圆环（每探测器对应一个圆环）扫描角频率平面，而是使用30个准直器，每个准直器对应特定角频率。本文推导了适用于STIX观测可见度数据的计算方法的改进版本，该方法还允许将观测计数数据划分至非均匀间隔的能量区间。研究表明，正则化成像光谱法不仅可用于分析STIX可见度数据，且其可靠性更优。通过对多个典型耀斑应用该技术，我们揭示了耀斑源区内电子通量谱的精细变化特征。结论表明，基于可见度的正则化成像光谱法完全适用于STIX数据分析。此外，我们首次利用STIX电子通量谱图像追踪了加速电子从日冕加速区向色球层传播过程中的行为特征。