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Searching for sub-second pulsations in X-ray flare data from Fermi/GBM

Presentation #106.14 in the session Solar Eruptive Events: Posters.

Published onSep 18, 2023
Searching for sub-second pulsations in X-ray flare data from Fermi/GBM

The presence of quasi-periodic pulsations is a well-documented feature of solar flare emission. Most commonly such features are observed with timescales in the 10 - 60s range. However, due to observational constraints it is less certain whether such pulsations are commonly found on timescales of 1s or less (e.g. Knuth et al. 2020). Fermi/GBM has observed over 1400 solar flares that triggered the creation of burst mode data products with a sampling rate of 16 Hz. This high-resolution dataset provides an ideal opportunity to search for pulsations at 1s timescales at both soft and hard X-ray energies. We use the AFINO analysis tool (Inglis et al. 2015, 2016) to analyze this entire dataset of 1400 flares in search of such features, adopting a ‘stepping-window’ approach to split and analyze each flare time series as a sequence of overlapping segments. Given the large number of input time series segments to be analyzed, we also apply AFINO to simulated flare time series — both with and without oscillatory signatures — in order to understand its detection capabilities and quantify the false alarm rate. Based on this analysis, we present case studies of solar flares with clear signatures of X-ray pulsations at timescales of 1 s.

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