Kavli Affiliate: Nicola Omodei
| First 5 Authors: Melissa Pesce-Rollins, Melissa Pesce-Rollins, , ,
| Summary:
We report on the $gamma$-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 $gamma$-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 $gamma$-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.
| Search Query: ArXiv Query: search_query=au:”Nicola Omodei”&id_list=&start=0&max_results=3