A Statistical Study to Determine the Origin of Long-duration Gamma-Ray Flares
A Statistical Study to Determine the Origin of Long-duration Gamma-Ray Flares
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确定长持续时间伽马射线耀斑起源的统计研究
DOI：
10.3847/1538-4357/aad3c0
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
M. Pesce
中科院分区：
文献类型：
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作者：
L. Winter;V. Bernstein;N. Omodei;M. Pesce
对于太阳耀斑中持续≥30 MeV的伽马射线发射，提出了两种可能的解释：(1)在耀斑区域涉及大规模磁环的长时间粒子加速/捕获，以及(2)在日冕/行星际激波中加速的高能（约300 MeV）质子的沉淀。为了确定哪一种情况更有可能发生，我们研究了相关的软x射线耀斑、日冕物质抛射（cme）和太阳高能质子事件(a)费米大面积望远镜观测到的长时间伽玛射线耀斑（LDGRFs），以及(b)太阳极大期任务上的伽玛-1望远镜上的伽玛射线光谱仪观测到的延迟和/或空间扩展的高能伽玛射线耀斑。以及康普顿伽马射线天文台的高能伽马射线实验望远镜。对于费米数据集的11个ldgrf， >00 MeV发射持续≥~ 2小时，我们搜索ldgrf， x射线耀斑，cme和SEPs之间的关联和反向关联，即从伽马射线耀斑开始，然后是x级软x射线耀斑，快速（≥1500 km s−1）和宽cme，强（峰值通量≥2.67 × 10−3质子cm−2 s−1 sr−1，峰值与背景比>1.38）>300 MeV SEPs在1 au。虽然LDGRF往往与明亮的x级耀斑有关，但我们发现，在费米监测期间，只有三分之一的x级耀斑与LDGRF相吻合。然而，几乎所有快速、广泛的日冕物质抛射都与LDGRF有关。这些初步的关联分析倾向于质子沉淀情景，尽管有一个突出的反例，即潜在的磁连接良好的太阳喷发，发射>100 MeV，持续约10小时，近地>300 MeV的质子强度没有上升到背景之上。
Two scenarios have been proposed to account for sustained ≥30 MeV gamma-ray emission in solar flares: (1) prolonged particle acceleration/trapping involving large-scale magnetic loops at the flare site, and (2) precipitation of high-energy (>300 MeV) protons accelerated at coronal/interplanetary shock waves. To determine which of these scenarios is more likely, we examine the associated soft X-ray flares, coronal mass ejections (CMEs), and solar energetic proton events for (a) the long-duration gamma-ray flares (LDGRFs) observed by the Large Area Telescope on Fermi, and (b) delayed and/or spatially extended high-energy gamma-ray flares observed by the Gamma-ray Spectrometer on the Solar Maximum Mission, the Gamma-1 telescope on the Gamma satellite, and the Energetic Gamma-Ray Experiment Telescope on the Compton Gamma-Ray Observatory. For the Fermi data set of 11 LDGRFs with >100 MeV emission lasting for ≥∼2 hr, we search for associations and reverse associations between LDGRFs, X-ray flares, CMEs, and SEPs, i.e., beginning with the gamma-ray flares and also, in turn, with X-class soft X-ray flares, fast (≥1500 km s−1) and wide CMEs, and intense (peak flux ≥2.67 × 10−3 protons cm−2 s−1 sr−1, with peak to background ratio >1.38) >300 MeV SEPs at 1 au. While LDGRFs tend to be associated with bright X-class flares, we find that only one-third of the X-class flares during the time of Fermi monitoring coincide with an LDGRF. However, nearly all fast, wide CMEs are associated with an LDGRF. These preliminary association analyses favor the proton precipitation scenario, although there is a prominent counter-example of a potentially magnetically well-connected solar eruption with >100 MeV emission for ∼10 hr for which the near-Earth >300 MeV proton intensity did not rise above background.