A LARGE-SCALE SEARCH FOR EVIDENCE OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARES
A LARGE-SCALE SEARCH FOR EVIDENCE OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARES
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DOI：
10.3847/1538-4357/833/2/284
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发表时间：
2016-10
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影响因子：
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通讯作者：
A. Inglis;J. Ireland;B. Dennis;L. Hayes;P. Gallagher
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作者：
A. Inglis;J. Ireland;B. Dennis;L. Hayes;P. Gallagher
太阳耀斑中的准周期脉动（QPP）的性质很少受到约束，而且这种信号在太阳耀斑中的普遍存在是未知的。因此，我们对太阳耀斑中与QPP一致的信号进行了大规模的搜索，重点是1 - 300s的时间尺度。本文分析了2011年2月1日至2015年12月31日期间地球静止运行环境卫星（GOES）系列在1 - 8 Å软x射线波段观测到的675颗M级和x级耀斑。此外，在同一时期，我们分析了费米/伽马射线爆发监测器（GBM） 15-25 keV的x射线数据，这些耀斑与费米/GBM太阳耀斑触发器相关，总共261个事件。使用模型比较方法，我们确定是否有证据表明傅里叶功率谱的实质性增强可能与QPP签名一致，基于三个测试模型；幂律加常数，破幂律加常数，以及带有附加QPP签名分量的幂律加常数。由此，我们确定~ 30%的GOES事件和~ 8%的Fermi/GBM事件显示出与经典QPP解释一致的强特征。对于剩余的事件，两个或更多的测试模型不能彼此强烈区分，或者事件被单幂律或破幂律傅里叶功率谱很好地描述。对于这两种仪器，在类似qpp的事件中发现了优选的特征时间尺度~ 5-30秒，与GOES或GBM数据中的耀斑量级无关。我们还表明，样本中的单个事件在GBM和GOES数据集中都显示出相似的特征时间尺度。我们讨论了这些结果对我们理解太阳耀斑和可能的QPP机制的意义。
The nature of quasi-periodic pulsations (QPP) in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with QPP in solar flares, focusing on the 1–300 s timescale. We analyze 675 M- and X-class flares observed by the Geostationary Operational Environmental Satellite (GOES) series in 1–8 Å soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyze Fermi/Gamma-ray Burst Monitor (GBM) 15–25 keV X-ray data for each of these flares associated with a Fermi/GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that ∼30% of GOES events and ∼8% of Fermi/GBM events show strong signatures consistent with classical interpretations of QPP. For the remaining events either two or more tested models cannot be strongly distinguished from each other, or the events are well-described by single power-law or broken power-law Fourier power spectra. For both instruments, a preferred characteristic timescale of ∼5–30 s was found in the QPP-like events, with no dependence on flare magnitude in either GOES or GBM data. We also show that individual events in the sample show similar characteristic timescales in both GBM and GOES data sets. We discuss the implications of these results for our understanding of solar flares and possible QPP mechanisms.