Spectral characteristics of fundamental pairs -Armonic of Interplanetary Rapagas Type III Radio observed by PSP, by Ling Chen et al. – European astronomer radio community

Radio Radio III bursts are the most powerful and common type of bursts of solar radius, which quickly change high to low frequencies. In addition to the drifting of rapid frequency of high at low frequencies, the structure of the fundamental -Amonic frequency (FH) in its dynamic spectra is the other most important observed feature of the type III solar radio explosions. In this letter, using the radio data observed by PSP during the meeting phases from the first orbit to the temporal resolutions of orbit of the ninth orbit (E01-E09) with 7 S (E01-E05) and the improved temporary resolutions of 3.5 S (E06-E09), we report, inform, we report the spectral characteristics representative of the FH pairs of the radio bursts Type III IP. These spectral characteristics can provide some restrictions of their source regions and will be useful for us to understand the physics of their formation.

Data observation and analysis

On the basis of the frequency derivation rate, the FH pairs of the Radio Radio IP type III can be divided into two categories, that is, the quasi-parallel FH pairs with frequency frequency speed curves quasi-oralla f and H (see, for example, Figure 2 (c)) and non -parallel FH pairs with frequency frequency speed curves F and H non -parallel, and the first is The dominant.

Comparison of the spectral characteristics of these f and h pairs, such as the frequency drift speed, emission intensity, relative bandwidth, duration and fine structure, can be divided into six typical types in the case of fh peers Frequently quasi parallel -the derivation rate (Figure 1 and Figure 2). However, since the mechanism for emission of radio explosions depends significantly on local plasma parameters in the source regions, the understanding of physics that causes the difference in spectral characteristics requires a more detailed analysis. In the present study, we are only trying to provide some preliminary interpretations for spectral characteristics based on the new emission mechanism of Electron Cyclotron Master (ECM) that takes into account the effects of Alfvén’s environmental waves (Wu et al. 2012, WU 2014, Chen et al. 2017, Chen et al. 2021) as a potential physical model of their formation as follows:

• F being a shorter duration than H: One of the possible reasons is that, according to the ECM emission mechanism, the radiation F is emitted in the frequency of electron cyclotron $ f_ {ce} $ of the local plasma, which is possibly very close to the frequency of electron plasma $ f_ {pe} $, and f only emits when the $ f_ {ce} $ is higher than the $ f_ {pe} $, while h is not restricted For this limitation. That is, F is more likely to be cut, which prevents continuing radiating.
• F being structured yh being soft: The emission of X mode in the frequency band F in general it cannot escape due to the lower emission frequency than the cut frequency in X mode Or, and the H components consist of emissions of mode or y mode X. Consequently, according to the new ECM emission model, components F seem to have considerable stretch marks due to a significant modulation of the growth rate of the growth of the mode or deduced by the Alfvén wave, while the H components have little stretch due to little effect on the X -The modification growth rate by Alfvén
• H emission intensity is greater or less than F: Based on the new ECM emission model, the growth rates of O1 waves (wave F in the O), O2 and X2 (second h waves in modes O and X), differently, not only depends sensitive of the local background plasma parameters and the speed distribution of fast electrons, but are also considerably modulated by the intensity of Alfvén’s environmental waves. This could probably be one of the main reasons why the relative intensity of components F and H varies in a dependent manner of individual events because the intensity of Alfvé’s environmental waves often varies greatly in the solar crown and the solar wind .
• H is of greater frequency bandwidth than F: In general terms, H’s bandwidth variation is twice than F with the same frequency change caused by magnetic or density disturbance. The fact that F has a lower radiation bandwidth than H may be due to its susceptibility to dispersion losses at lower frequencies. Alternatively, component F with lower frequencies below the noise level has been subtracted because the noise level increases as the frequency decreases (Jebaraj et al. 2023).

Figure 1. Six typical FH pairs of bursts of Radio IP type III observed by PSP. (a) FH pairs with similar spectral characteristics between F and H (event 1). (b) The fh peers with F are structured and H are soft (event 2). (c) fh even with f being f shorter than H (event 3). (d) FH pairs with H emission intensity are higher than F (event 4). (E) fh pairs with H being a bandwidth wider than F (event 5). (f) fh even with the intensity of emission of F being higher than H (event 6). Adapted from Chen et al. (2024)

Figure 2. The spectral characteristics of the six FH couples explode radio. Panels (a)-(b) and (c) show the frequency ratio fh $ f_h/f_f $ and the frequency drift rate $ d_ {abs} $. The maximum flow densities corresponding to each frequency given $ \ mathrm {flux_ {tmax}} $ for events 1–6 are shown in the panels (d) – (i), respectively. The panels (J) – (O) present the relative bandwidth depending on the central frequency for events 1–6, respectively. The colors black, blue, orange, purple, green and red denote events 1–6 shown in figures 1 (a) – (f), respectively. The results that represent H change to the frequency of $ F_h/2 $.

Conclusions

The result shows that the rate of occurrence of FH peers increases significantly with the increase in the number of Rad radius type III detected by the PSP or the improvement in the time resolution of the RFS instrument. Specifically, the relative occurrence rate of FH peers increases (ie, ∼50%) as the amount of radius bursts type III increased by PSP or measure that increases the resolution of time of the RFS, such as PSP during E02 and E07- E09.

The results also show that in most FH pairs, components F have a more obvious stretch marks structure, shorter duration and a narrower bandwidth compared to H. In addition, the relative intensities of the components F and H of these fh peers exhibit complex variations, including the strongest component, the strongest H component, as well as the components F and H with almost identical intensity. The detailed and comprehensive training mechanisms of the FH peers of Radio IP type III explosions are closely related to local plasma conditions, including AW environmental fluctuations, in the source region and it is worth discussing in future works.

Based on the recent article by Ling Chen, Bing Ma, Dejin Wu, Zongjun Ning, Xiaowei Zhou and Stuart D. Bale, Spectral characteristics of fundamental pairs -Armonic of interplanetary bursts of type III radio observed by PSPAPJL, 975: L37, 2024. DOI: 10.3847/2041-8213/AD89C2

References

Chen, L., Ma, B., Wu, D., et al. 2021, APJL, 915, L22

Chen, L., Wu, DJ, Zhao, GQ, et al. 2017, Jgra, 122, 35

WU, CS, Wang, CB, WU, DJ, et al. 2012, pHPL, 19, 082902

WU, DJ 2014, pHPL, 21, 064506

Jebaraj, IC, Krasnososkikh, V., Pulupa, M., et al. 2023, APJL, 955, L20