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arXiv · 2106.09506

Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT

P. Zhang·W. Wang·Y. Su·L. M. Song·C. K. Li·D. K. Zhou·S. N. Zhang·H. Tian·S. M. Liu·H. S. Zhao·S. Zhang
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Abstract

The X9.3 flare SOL20170906T11:55 was observed by the CsI detector aboard the first Chinese X-ray observatory Hard X-ray Modulation telescope (Insight-HXMT). By using wavelets method, we report about 22 s quasiperiodic pulsations(QPPs) during the impulsive phase. And the spectra from 100 keV to 800 keV showed the evolution with the gamma-ray flux, of a power-law photon index from $\sim 1.8$ before the peak, $\sim 2.0$ around the flare peak, to $\sim 1.8$ again. The gyrosynchrotron microwave spectral analysis reveals a $36.6 \pm 0.6 \arcsec$ radius gyrosynchrotron source with mean transverse magnetic field around 608.2 Gauss, and the penetrated $\ge$ 10 keV non-thermal electron density is about $10^{6.7} \mathrm{cm}^{-3}$ at peak time. The magnetic field strength followed the evolution of high-frequency radio flux. Further gyrosynchrotron source modeling analysis implies that there exists a quite steady gyrosynchrotron source, the non-thermal electron density and transverse magnetic field evolution are similar to higher-frequency light curves. The temporally spectral analysis reveals that those non-thermal electrons are accelerated by repeated magnetic reconnection, likely from a lower corona source.

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P. Zhang, W. Wang, Y. Su, L. M. Song, C. K. Li, D. K. Zhou, S. N. Zhang, H. Tian, S. M. Liu, H. S. Zhao, S. Zhang. 2021-06-17. Non-thermal electron energization during the impulsive phase of an X9.3 flare revealed by Insight-HXMT. https://doi.org/10.3847/1538-4357%2Fac0cfb

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