Identification of Multiple Hard X-Ray Sources in Solar Flares: A Bayesian Analysis of the 2002 February 20 Event
Identification of Multiple Hard X-Ray Sources in Solar Flares: A Bayesian Analysis of the 2002 February 20 Event
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DOI：
10.3847/1538-4357/aacc27
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发表时间：
2018-07-20
影响因子：
4.9
通讯作者：
Piana, Michele
中科院分区：
文献类型：
--
作者：
Sciacchitano, Federica;Sorrentino, Alberto;Piana, Michele
太阳耀斑中的硬X射线发射。典型的特征在于多个离散源，每一个都具有其自身的光谱、时间和空间变化性。建立这些来源之间的关系是至关重要的，以确定每个在耀斑内发生的能量释放和传输过程中的作用。在本文中，我们提出了一种新的方法来识别和表征每个源的硬X射线发射。该方法允许的子源的最有可能的数量存在的定量测定，和相对概率的硬X射线发射在一个给定的子区域的耀斑是由一个复杂的多源结构或由一个简单的单源表示。我们将该方法应用于2002年的一个研究良好的耀斑。2月20日，为了评估关于色球足点源数量的竞争性声明，从而评估潜在的磁几何/拓扑结构的复杂性。与以前声称需要多个源来解释不同位置和时间的色球硬X射线发射相反，我们发现一个简单的双足点加日冕源模型是对数据最可能的解释。我们还发现，其中一个足迹源在整个事件中移动得相当快，这一因素可能使以前的分析复杂化。推断的足点速度对应于一个非常高的感应电场，兼容薄重连电流片的领域。
The hard X-ray emission in a solar flare. is typically characterized by a number of discrete sources, each with its own spectral, temporal, and spatial variability. Establishing the relationship among these sources is critical to determining the role of each in the energy release and transport processes that occur within the flare. In this paper we present a novel method to identify and characterize each source of hard X-ray emission. The method permits a quantitative determination of the most likely number of subsources present, and of the relative probabilities that the hard X-ray emission in a given subregion of the flare is represented by a complicated multiple source structure or by a simpler single source. We apply the method to a well-studied flare on 2002. February 20 in order to assess competing claims as to the number of chromospheric footpoint sources present, and hence to the complexity of the underlying magnetic geometry/topology. Contrary to previous claims of the need for multiple sources to account for the chromospheric hard X-ray emission at different locations and times, we find that a simple two-footpoint-plus-coronal-source model is the most probable explanation for the data. We also find that one of the footpoint sources moves quite rapidly throughout the event, a factor that presumably complicated previous analyses. The inferred velocity of the footpoint corresponds to a very high induced electric field, compatible with the fields in thin reconnecting current sheets.