DRIFTS periods and frequencies of groups of decimetric picos of narrow band by M. Karlický, J. Dudík and J. Rybák – Community of radio astronomers solar European

The narrow band decimetric peaks belong to the most interesting solar radio bursts, because they are connected to the primary flashes process. Its brightness temperature is up to 10¹⁵ K. In the radio spectrum, they occur in clouds of many narrow band explosions with a relative bandwidth of approximately 1-3 % and a duration of less than 100 ms (Benz, 1986). Many models of these peaks were proposed, such as those based on the Master mechanism of electron cyclotron or based on the plasma emission mechanism. Karlický et al. (1996) He studied the frequency band widths of the peaks by the Fourier method. They found the spectra of the power law with power law rates near -5/3, the Kolmogorov turbulence index. Therefore, it was suggested that peaks are generated by supratermic electrons in magnetohydrodynamic turbulence.

Figure 1. Superior: Radio spectrum observed at 13:41:30 – 13:42:30 UT during the flare of May 10, 2022. Below: its detail at 13:42:00 – 13:42:03 UT. The white line marks an example of the frequency drift of these peaks. The black horizontal lines in both spectra show the frequency at which the periods were analyzed.

Figure 2. SDO/AIA 171 An observation of the reconnect of threads (1 red and 2 blue) at the time of the DM strikes at 13:42:09 UT, also watch the movies in our article.

Observations and results

We study the radio broadcast that occurs as decimetric picos of narrow band observed during the 2022 of May 10 and 2022, the flares of August 26. Using the Wavelet analysis technique, we found that the peaks in their radio spectra were distributed in groups that occurred quasi periodically with periods 5.1 s in the Bengal of May 10, 2022 and 9.1 s in the flare of August 26, 2022 .

In some parts of the peak groups, subgroups of spikes were found with the quasi-perories of 0.19 s (May 2022, May 10), and 0.17 Sy 0.21 S (August 2022 26 of sprouts). Some of these peak subgroups had a positive frequency drift (930, 1100 and 1710 MHz S^-1), while others had a negative drift (−1000 and -1330 MHz S -1), which was first observed. An example of subgroups with the quasi period of 0.19 s observed during May 2022 10 is shown in Figure 1. There, the peaks are derived from lower to higher frequencies, as indicated by the White Line.

The peaks at 13:42 UT of the 2022 of May 10 occurred during the precursor phase of the X1.5 X1 x1 X-ray Bengal as registered by GOES-16. At the time of the observation of the peaks, a couple of short loops and mutually identified that interact in the observations of SDO/AIA EUV. One of these loops was interpreted as a brilliant thread that belongs to the small filament in eruption, while the other loop was an opposition -oriented overlap loop, see Figure 2.

Conclusions

We propose that the mentioned loops are connected again in the quasi -newspaper dynamic regime with the period 0.19 s, and that this reconnection is modulated by an oscillation of one of the interactive loops (period 5.1 s). We observe that the similar periods of the Spike Group (0.1-0.9 s) were also recently found by Huang et al. (2022).

The drift of peak groups was observed for the first time. According to Karlický et al. (1996)We propose that the accelerated electrons of the reconnection process are trapped in the reconnect plasma outputs and move with them. Due to this movement, the sources of peaks moved to plasma densities higher or lower, and therefore the peak drift groups were generated.

During 2022, on August 26, similar periods were found and derives from peak groups. However, the magnetic structure of the Bengal in the SDO/AIA images was quite complex, which hinders the difficult identification of identification reconnect structures in a unique way as in the Bengal of May 10, 2022. However, we find indications that the groups of peaks and their derivations were generated by similar processes that in the Bengal of May 10, 2022.

Based on the article published in Solar Physics 299: 113 (2024) By Marian Karlický, Jaroslav Dudík and Ján Rybák

References

Benz, year, 1986, Solar Phys. 104, 9

Huang, J., Tan, C., Chen, X. et al., 2022, Universe 8, 348

Karlický, M., Sobotka, M., Jičička, K., 1996, Solar Phys. 168, 375