Drifting tadpoles in wavelet spectra of decimetric radio emission of fiber bursts
Authors:
H. Meszarosova, M. Karlicky, J. Rybak, K. Jiricka
Image & caption:
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Image caption::
Characteristic examples of wavelet power spectra with tadpole patterns
detected in four selected radio frequencies. Tadpoles are outlined
by contours at the 99% significance. The dashed line represents time
of the head tadpole maximum at 1752 MHz. The dotted line shows the
frequency drift towards lower frequencies.
Description:
The solar decimetric radio emission of fiber bursts was investigated
searching for the "drifting tadpole" structures proposed by theoretical
studies.
Characteristic periods with the tadpole pattern were
searched for in the radio flux time series by wavelet analysis
methods.
For the first time, we have found drifting tadpoles in the
wavelet spectra of the decimetric radio emission associated with the
fiber bursts observed in July 11, 2005. These tadpoles were detected
at all radio frequencies in the 1602-1780 MHz frequency range. The
characteristic period of the wavelet tadpole patterns was found to
be 81.4 s and the frequency drift of the tadpole heads is -6.8 MHz s-1. These tadpoles are interpreted as a signature of the magnetoacoustic
wave train moving along a dense flare waveguide and their frequency
drift as a motion of the wave train modulating the radio emission
produced by the plasma emission mechanism. The present analysis
supports the model of fiber bursts based on whistler waves.
SK
SAS
