Gamma-Ray Emission from the Impulsive Phase of the 2017 September 6 X9.3 Flare
Gamma-Ray Emission from the Impulsive Phase of the 2017 September 6 X9.3 Flare
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DOI：
10.3847/1538-4357/ab1be0
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发表时间：
2019-04
期刊：
影响因子：
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通讯作者：
A. Lysenko;S. Anfinogentov;D. Svinkin;D. Frederiks;G. Fleishman
中科院分区：
文献类型：
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作者：
A. Lysenko;S. Anfinogentov;D. Svinkin;D. Frederiks;G. Fleishman
我们报告了SOL2017-09-06T11:55 X9.3太阳耀斑脉冲阶段的硬x射线和伽马射线观测。我们将重点放在光谱的高能部分，bbb100 keV，并对Konus-Wind实验记录的脉冲相位的一部分进行时间分辨光谱分析，该部分显示出突出的伽马射线发射。鉴于各种可能的发射成分有助于伽马射线发射，我们采用贝叶斯推理来建立最可能的拟合模型。分析自信地揭示了核去激发线、511 keV的电子-正电子湮灭线和2.223 MeV的中子俘获线以及轫致辐射连续体的两个组成部分的贡献。所揭示的光谱成分的时间演化是特别有趣的。低能韧致辐射连续体表现为脉冲耀斑典型的软-硬-软模式，而高能韧致辐射连续体在耀斑过程中表现为持续硬化。中子俘获线发射相对于核去激发线分量显示出异常短的时间延迟，这意味着中子的产生在事件发生后不久就显著减少。这反过来可能意味着在耀斑过程中加速质子谱的显著软化，类似于导致低能轫致辐射连续体的加速电子的低能成分的软化。我们讨论了可能的物理场景，这可能导致这些伽马射线成分之间的关系。
We report hard X-ray and gamma-ray observations of the impulsive phase of the SOL2017-09-06T11:55 X9.3 solar flare. We focus on a high-energy part of the spectrum, >100 keV, and perform time resolved spectral analysis for a portion of the impulsive phase, recorded by the Konus-Wind experiment, that displayed prominent gamma-ray emission. Given a variety of possible emission components contributing to the gamma-ray emission, we employ a Bayesian inference to build the most probable fitting model. The analysis confidently revealed contributions from nuclear deexcitation lines, electron–positron annihilation line at 511 keV, and a neutron capture line at 2.223 MeV along with two components of the bremsstrahlung continuum. The revealed time evolution of the spectral components is particularly interesting. The low-energy bremsstrahlung continuum shows a soft–hard–soft pattern typical for impulsive flares, while the high-energy one shows a persistent hardening at the course of the flare. The neutron capture line emission shows an unusually short time delay relative to the nuclear deexcitation line component, which implies that the production of neutrons was significantly reduced soon after the event onset. This in turn may imply a prominent softening of the accelerated proton spectrum at the course of the flare, similar to the observed softening of the low-energy component of the accelerated electrons responsible for the low-energy bremsstrahlung continuum. We discuss possible physical scenarios, which might result in the obtained relationships between these gamma-ray components.