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Spectroscopic diagnostics of the non-Maxwellian κ-distributions using SDO/EVE observations of the 2012 March 7 X-class flare View all abstracts by submitter

Jaroslav Dud   Submitted: 2018-01-10 01:10

Spectroscopic observations made by the Extreme Ultraviolet Variability Experiment (EVE) on board the Solar Dynamics Observatory (SDO) during the 2012 March 7 X5.4-class flare (SOL2012-03-07T00:07) are analyzed for signatures of the non-Maxwellian kappa-distributions. Observed spectra were averaged over 1 minute to increase photon statistics in weaker lines and the pre-flare spectrum was subtracted. Synthetic line intensities for the kappa-distributions are calculated using the KAPPA database. We find strong departures (kappa < 2) during the early and impulsive phases of the flare, with subsequent thermalization of the flare plasma during the gradual phase. If the temperatures are diagnosed from a single line ratio, the results are strongly dependent on the value of kappa. For kappa=2, we find temperatures about a factor of two higher than the commonly used Maxwellian ones. The non-Maxwellian effects could also cause the temperatures diagnosed from line ratios and from the ratio of GOES X-ray channels to be different. Multithermal analysis reveals the plasma to be strongly multithermal at all times with flat DEMs. For lower kappa, the DEM_kappa are shifted towards higher temperatures. The only parameter that is nearly independent of kappa is electron density, where we find log(N_e) ≈ 11.5 almost independently of time. We conclude that the non-Maxwellian effects are important and should be taken into account when analyzing solar flare observations, including spectroscopic and imaging ones.

Authors: Elena Dzifcakova, Alena Zemanova, Jaroslav Dudik, and Simon Mackovjak
Projects: SDO-EVE

Publication Status: ApJ, accepted
Last Modified: 2018-01-10 11:25
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