L. K. Kashapova, N. S. Meshalkina, M. S. Kisil
We present an analysis of the plasma parameters during the initial phase of the 12 June 2010 flare (SOL2010-06-12T00:57). A peculiarity of the flare was the detection of $\gamma$--emission that is unusual for such weak and short event. The analysis revealed the presence of a flare precursor detected about 5 minutes before the flare onset in 94 \AA \ images which spatially coincided with the non-polarized microwave (MW) source at 17 GHz (\textit{the Nobeyama Radio Heliograph}) that is the Neutral Line associated Source (NLS). A comparison of the results obtained from MW data by \textit{the Nobeyama Radio Polarimeters} and \textit{the multi-frequency Siberian radioheliograph} (the new 10-antenna radio heliograph prototype at 4.6 and 6.4 GHz) and hard X-ray (HXR) observations by \textit{the Fermi Gamma-ray Space Telescope} reveal the presence of accelerated electrons during the flare initial phase. The analysis of MW and HXR spectra also confirms the presence of accelerated particles. Moreover a good temporal correlation between several lightcurves in different HXR energy bands and at MW frequencies indicates generation of both HXR and MW emission by a common population of accelerated electrons. Detection of accelerated particles during the initial phase of the flare and soft-hard-harder (SHH) behavior of the spectra indicate several episodes of particle acceleration and confirm the non-impulsive type of the flare evolution.
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http://arxiv.org/abs/1207.5896
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