Analysis of Individual Terrestrial Gamma‐Ray Flashes With Lightning Leader Models and Fermi Gamma‐Ray Burst Monitor Data
Analysis of Individual Terrestrial Gamma‐Ray Flashes With Lightning Leader Models and Fermi Gamma‐Ray Burst Monitor Data
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利用闪电先导模型和费米伽马射线暴监测数据分析单个地面伽马射线闪光
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发表时间：
2019
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通讯作者：
M. Stanbro
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作者：
B. Mailyan;W. Xu;S. Celestin;M. S. Briggs;J. Dwyer;E. Cramer;O. Roberts;M. Stanbro
费米飞船上的伽马射线暴监视器(GBM)已经观测到数十个足够明亮的事件，适合单独分析。在我们之前的研究中，我们首次用相对论逃逸电子雪崩(RREA)模型对单个明亮的地面伽马射线闪光(TGFs)进行了拟合。对于基于相对论反馈的模型，产生转化生长因子的电子在内部由正反馈效应播种，通常在具有充分发展的RREA的大范围场中加速。或者，闪电先导模型既可以适用于雷暴区域完全发育的大尺度雷暴场，也可以适用于雷电先导前的不均匀场，其中雷暴先导区域只有部分发育。对后一种非齐次模型的预测与相对论反馈模型在均匀场中的估计有所不同。在这项工作中，我们在闪电先导模型的框架下分析了66个明亮的费米GBM TGFs，并与以前的均匀场RREA模型的结果进行了比较。在大多数情况下，频谱分析并不强烈倾向于一种机制而不是另一种机制，59%的转化生长因子事件最适合完全发展的RREA机制，这对应于高潜力的领导者模型。如果震源高度低于15公里，大多数GBM测量的TGFs可以得到最好的拟合，并且除非使用倾斜的光子束，否则70%的由Leader模型最好地拟合的事件无法令人满意地模拟。对于几种光谱较软的TGFs，倾斜梁低电势引线模型能最好地拟合数据。
The Gamma‐ray Burst Monitor (GBM) onboard the Fermi spacecraft has observed many tens of sufficiently bright events, which are suitable for individual analysis. In our previous study, we fit individual, bright terrestrial gamma‐ray flashes (TGFs) with Relativistic Runaway Electron Avalanche (RREA) models for the first time. For relativistic‐feedback‐based models, the TGF‐producing electrons, which are seeded internally by a positive feedback effect, are usually accelerated in a large‐scale field with fully developed RREAs. Alternatively, lightning leader models may apply to either a large‐scale thunderstorm fields with fully developed RREAs or to inhomogeneous fields in front of lightning leaders where RREAs only develop partially. The predictions of the latter, inhomogeneous models for the TGF‐beaming geometry show some differences from estimations of the relativistic feedback models in homogeneous fields. In this work, we analyze a large sample of 66 bright Fermi GBM TGFs in the framework of lightning leader models, making comparisons with previous results from the homogeneous‐field RREA models. In most cases, the spectral analysis does not strongly favor one mechanism over the other, with 59% of the TGF events being best fit with the fully developed RREA mechanism, which corresponds to high‐potential leader models. The majority of the GBM‐measured TGFs can be best fit if the source altitude is below 15 km and 70% of events best fit by leader models cannot be satisfactorily modeled unless a tilted photon beam is used. For several spectrally soft TGFs, the tilted beam low‐potential leader model can best fit the data.