Article Dans Une Revue The Astrophysical Journal Année : 2025

Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration

Résumé

We report on the $γ$-ray emission above 100~MeV from the GOES M3.3 flare SOL2012-06-03. The hard X-ray (HXR) and microwave emissions have typical time profiles with a fast rise to a well-defined peak followed by a slower decay. The $>$100~MeV emission during the prompt phase displayed a double-peaked temporal structure with the first peak following the HXR and microwaves, and the second one, about three times stronger, occurring $17 \pm 2$ seconds later. The time profiles seem to indicate two separate acceleration mechanisms at work, where the second $γ$-ray peak reveals a potentially pure or at least largely dominant ion acceleration. The Atmospheric Imaging Assembly imaging shows a bright elliptical ribbon and a transient brightening in the north-western (NW) region. Nonlinear force-free extrapolations at the time of the impulsive peaks show closed field lines connecting the NW region to the south-eastern part of the ribbon and the magnetic topology revealed clusters of nulls. These observations suggest a spine-and-fan geometry, and based on these observations we interpret the second $γ$-ray peak as being due to the predominant acceleration of ions in a region with multiple null points. The $>$100 MeV emission from this flare also exhibits a delayed phase with an exponential decay of roughly 350 seconds. We find that the delayed emission is consistent with ions being trapped in a closed flux tube with gradual escape via their loss cone to the chromosphere.

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hal-05185160 , version 1 (16-08-2025)

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Melissa Pesce-Rollins, Alexander Mackinnon, Karl-Ludwig Klein, Alexander Russell, Hugh Hudson, et al.. Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration. The Astrophysical Journal, 2025, 989 (2), pp.148. ⟨10.3847/1538-4357/adeb7f⟩. ⟨hal-05185160⟩
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