Non -linear evolution of the instability of two electron transmissions, by AO Benz et al. – European astronomer radio community

The solar type V radius bursts are continuous broadband associated with type III bursts, which are generally believed to be caused by coronal electrons. Ráfagas of type V sometimes appear for 0.2 to 3 minutes as a continuum after an intense explosion of type III or a group of explosions.

The spectral peak of type V bursts is generally less than 100 MHz. The high frequency edge is below the starting frequency of the associated type III explosion, and the low frequency limit is often less than that of Terrestrial spectrometers (20-40 MHz). The initial and initial edges are generally derived, but not always of high at low frequencies. Therefore, the combination of a burst type V and III has the form of a flag in a post in the spectrogram. Stewart (1978) Reports that bursts of type III/V are better correlated with hard x -ray shoots than type III bursts (80% compared to 20%), which suggests more powerful events. In some cases, there is a time gap between type III gust and the beginning of type V broadcast. Such cases are called separate events. The circular polarization of type V bursts is weak (of order 10% or less). Dulk, Gary and Suzuki (1980) report that it is generally invested compared to the gust of type III above.

Electron beams are unstable langmuir waves of two flows and transmission that are joined in radio waves (type III burst). In the non-linear phase, the distribution of electrons becomes quasi-station and elongated in the front. It has been predicted that this distribution is unstable towards the instability of the manifestation of electrons that involve resonant protons and for large anisotropies also resonant electrons (Pilipp and Benz 1977). Secondary instability then disperses the electrons of the beam in a transverse direction. It can be speculated that isotropic electrons develop a cone of precipitation losses and become unstable for the emission of Radio Masear.

Che et al. (2014) They have simulated the non -linear evolution of electron handle by cell particles (PIC) and have found evidence of the sequence of instabilities that lead to radio emission and radio dispersion type III. After an early phase dominated by the growing Langmuir waves, the instability of two electron transmissions drives the waves not propagated from Weibel that excite the kinetic alfvén waves and whistle waves by wave waves. These kinetic processes disperse beam electrons in transverse direction.

Here we present an extraordinary type V event and ask the question: can this whole type III/V event be explained by phenomena originated from the non -linear evolution of the instability of two currents?

Observations

Flare Sol2021-05-07T03: 39 was selected for its combination of a burst of U-type wave waves followed by a V-gust. The event was observed by several stations of the e-Calisto network. We use ASSA data in Sunnydale (Australia). The spectrometer was programmed to observe the frequency range of 15 to 87 MHz with a resolution of 0.375 MHz. The calibration is not available.

Figure 1 shows a general description of radio emission. The background was determined in low fluctuations time intervals for 30 minutes before and after the explosions. The 5%quantile of the flow was used as the bottom and remained.

The emission structures in the spectrogram are characterized by their maximum flow over time. Peak time is determined from Gaussian adjustments in each frequency. The highest peak is selected at each frequency and its peak time is recorded. The values ​​define a curve in the spectrogram (ν, t) -Space). The results are shown in Figure 1 (below) and are used in Figure 1 (above) to identify structures.

Figure 1: Below: The spectrogram that shows the radius flow with U Burst (event 3) and the type V gust (event 4) in unories. Black crosses “X” mark a local flow in time for bursts type III UND U. For type V emission, the “X” indicates the starting point of the emission at a given frequency. Above: Relationship between left and right circular polarization.

Figure 2: U Burche: Blue points: peak times in the frequency channel. Red curves: equipped to the beak.

Figure 3: Type V: Blue points indicate times of 8% increase above the bottom. Red curves: equipped on the edge of start.

Results and Discussion

1. Derivation rate

The drift of the descending branch of the Burst U is -0.30 [s^-1]. For a 10 density scale height¹⁰Cm (2 mk) and plasma emission, the speed of the beam is 6 · 10⁹ cm/s. The start of the type V burst travels with -0.15 [s^-1]. If the emission process is plasma emission, the drift speed of the initial edge type V is half of the B whatst U. If the emission is electron cyclotron master and the height of the magnetic scale is the same as the same as The height of the density scale, the speed is 1/4 of the Burst U beam. For both issues, the data suggests that the electrons that cause type V have a lower speed than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons than the electrons They cause type III.

2. Begin of events

The starting edge of type V broadcast begins around 03:40:23 UTC, coinciding with the

BURST U Loop Apex, therefore, type V emission begins when the electron beam passes the apex of the loop.

3. Circular polarization

Figure 1 The upper part indicates that the polarization of the U -type gust is compatible with zero,

However, the polarization of the type V gusts is allowed to circulate (green). Therefore, type III and type V emissions can be caused by different mechanisms.

Scenario and conclusions

U Bursst data (event 3) and type V burst (event 4) can be combined in a

Coherent scenario:

1. The electrons accelerate near the foot points of a magnetic loop. An electrons is propagated along a coronal loop.

2. The ray is of two transmissions unstable and exciting Langmuir waves. They collapse in the acoustic waves of exciting ions of non -linear phase. Wave wave coupling produces radio emission, which is observed as bursts of type III und Und.

3. The speed distribution of a beam is preferably parallel, promoting the electron Hose instability. In the non -linear phase, it corresponds to an exciting weibel and Hender Waves, which disperse energetic electrons in perpendicular speed. Non -thermal electrons form an isotropic halo.

4. After the beam has passed, the distribution of quasi -isotropic electrons is deformed, losing electrons in parallel direction that escape and precipitate.

5. The energetic electrons develop a loss cone distribution. It becomes unstable Electron Master emission and causes an emission of V -radius at frequencies above the plasma frequency.

This scenario suggests a complex interaction of several kinetic plasma processes.

Image simulations have been inspiring, but they are still too limited to confirm the stage.

More image observations of the spatial relationship between bursts III/U and V are also necessary.

Based on the recent article: Benz, Ao, · Huber, Cr, Timmel, V., Monstein, C. Observation of an extraordinary type V radio explosion: non -linear evolution of the instability of two electron transmissions: Solar Physics, 299, 146 (2024). https://doi.org/10.1007/S11207-024-02395-8

References

Che, H., Goldstein, ML, Vinas, AF 2014, Phys. Rev. Lett., 112, 061101.

Dulk, Ga, Gary, by, Suzuki, S. 1980, A&A, 88, 218.

Pilipp, WG, Benz Ao 1977, A & a, 56, 39.

Stewart RT 1978, Solar Phys,. 58, 121.