Investigation of the Neupert effect in solar flares. I. Statistical properties and the evaporation model

By A. Veronig, B. Vršnak, Brian R. Dennis, M. Temmer, A. Hanslmeier, Jasmina Magdalenic. 2002

137 citations recorded by the source corpus.

Based on a sample of 1114 flares observed simultaneously in hard X-rays (HXR) by the BATSE instrument and in soft X-rays (SXR) by GOES, we studied several aspects of the Neupert eect and its interpretation in the frame of the electron- beam-driven evaporation model. In particular, we investigated the time dierences (t) between the maximum of the SXR emission and the end of the HXR emission, which are expected to occur at almost the same time. Furthermore, we performed a detailed analysis of the SXR peak flux - HXR fluence relationship for the complete set of events, as well as separately for subsets of events which are likely compatible/incompatible with the timing expectations of the Neupert eect. The distribution of the time dierences reveals a pronounced peak att = 0. About half of the events show a timing behavior which can be considered to be consistent with the expectations from the Neupert eect. For these events, a high correlation between the SXR peak flux and the HXR fluence is obtained, indicative of electron-beam-driven evaporation. However, there is also a significant fraction of flares (about one fourth), which show strong deviations fromt= 0, with a prolonged increase of the SXR emission distinctly beyond the end of the HXR emission. These results suggest that electron-beam-driven evaporation plays an important role in solar flares. Yet, in a significant fraction of events, there is also clear evidence for the presence of an additional energy transport mechanism other than nonthermal electron beams, where the relative contribution is found to vary with the flare importance.

Subfields: Astronomy and Astrophysics, Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/47554043ebe72a723e5a3589ea708f7dd6180aec

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In Astronomy and Astrophysics

Citations in the corpus

An Observational Overview of Solar Flares (2011, background): “…andCGRO/BATSE HXR counts at 25-50 and 50-100 keV, found that 50% of events were consistent with Neupert-like timing behavior,25% were inconsistent, with SXR 8 Fletcher et al. emission peaking substantially after the end of the HXR emission, and the remaining 25% were unclear (Veronig et al. 2002a).”
Implications of X-ray Observations for Electron Acceleration and Propagation in Solar Flares (2011, methodology): “A high correlation and time coincidence between the soft X-ray peak and hard X-ray end time was generally found, but a significant fraction of events also had a different timing (Veronig et al. 2002c).”