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arXiv · 2003.05007

Subsecond Spikes in Fermi GBM X-ray Flux as a Probe for Solar Flare Particle Acceleration

Trevor Knuth·Lindsay Glesener
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Abstract

Solar flares are known to release a large amount of energy into accelerating electrons. Studying small timescale ($\leq$ 2s) fluctuations in nonthermal X-ray flux offers the opportunity to probe the nature of those acceleration mechanisms. By comparing the durations, differences in timing between energy bands, and the periodicity of these spikes against the relevant timescales called for by various acceleration mechanisms, a test for each mechanism's validity can be made. This work details the analysis of fast fluctuations in Fermi Gamma-ray Burst Monitor (Fermi GBM) data from 2 M9.3 class solar flares that occurred on SOL2011-07-30 and SOL2011-08-04. This study shows the usefulness of Fermi GBM data as a means of examining these small timescale spikes and presents a rigorous method of identifying, counting, and measuring the temporal properties of these subsecond X-ray spikes. In the 2 flares examined we found spikes to primarily occur in spans of 60-100 seconds in the impulsive phase. The relative spike intensity ranged from 5% to 46% of the total counts, depending on the energy band the spike was measured in. The average spike durations were 0.96 and 0.66 seconds and the median durations were 0.79 and 0.32 seconds for the 2 flares. The spike duration distribution for the SOL2011-08-04 flare was found to follow a power law with a -1.8 $\pm$ 0.5 index. Of the 3 spiking intervals identified, only 1 was found to have a periodicity, showing significant power at the 1.7 $\pm$ 0.1 Hz frequency.

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Trevor Knuth, Lindsay Glesener. 2020-09-08. Subsecond Spikes in Fermi GBM X-ray Flux as a Probe for Solar Flare Particle Acceleration. https://doi.org/10.3847/1538-4357%2Fabb779

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