Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15 |
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Laurent Dolla Submitted: 2012-03-28 04:54
We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 15 February
2011, observed simultaneously in several wavebands. We focus on fluctuations on time scale 1?30 s
and find different time lags between different wavebands. During the impulsive phase, the Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) channels in the range 25x100 keV lead
all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and
the Extreme Ultra-Violet (EUV) channels of the Euv SpectroPhotometer (ESP) onboard the Solar
Dynamic Observatory (SDO). The Zirconium and Aluminum filter channels of the Large Yield Radiometer
(LYRA) onboard the Project for On-Board Autonomy (PROBA2) satellite and the SXR
channel of ESP follow. The largest lags occur in observations from the Geostationary Operational
Environmental Satellite (GOES), where the channel at 1?8 ? leads the 0.5?4 ? channel by several
seconds. The time lags between the first and last channels is up to 9 s. We identified at least two
distinct time intervals during the flare impulsive phase, during which the QPPs were associated with
two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard
X-ray channels showed different lags during these two intervals. To our knowledge, this is the first
time that time lags are reported between EUV and SXR fluctuations on these time scales. We discuss
possible emission mechanisms and interpretations, including flare electron trapping.
Authors: L. Dolla, C. Marqué, D. B. Seaton, T. Van Doorsselaere, M. Dominique, D. Berghmans, C. Cabanas, A. De Groof, W. Schmutz, A. Verdini, M. J. West, J. Zender and A. N. Zhukov
Projects: Nobeyama Radioheliograph,PROBA2/LYRA,RHESSI,SDO-AIA,SDO-EVE
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Publication Status: ApJ (published)
Last Modified: 2012-03-28 09:04
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