Saint Petersburg, Russian Federation
St. Petersburg, Russian Federation
UDC 523.98
This paper examines errors in recovering (radio diagnostics) solar flare parameters (magnetic field, accelerated electron density, etc.) by fitting microwave spectra. The analysis was performed by diagnosing two model radio sources with known preset parameters, including given parameters of the pitch-angle anisotropy of emitting electrons. The diagnostics was carried out by a genetic minimization algorithm. It is shown that using the traditional approach on the assumption about isotropy of pitch angular distribution of electrons leads to significant systematic errors, in particular, to a strong underestimation of the magnetic field strength in the presence of longitudinal anisotropy of pitch angular distribution of electrons in a real radio source. When restoring the same parameters in view of possible anisotropy, the accuracy of the restoration increases markedly.
solar flares, radioheliograph, radio diagnostics
1. Altyntsev A.T., Lesovoi S.V., Globa M.V., et al. Multiwave Siberian Radioheliograph. Sol.-Terr. Phys. 2020, vol. 6, iss. 2, pp. 30–40. https://doi.org/10.12737/stp-62202003.
2. Chen B., Yu S., Reeves K.K., Gary D.E. Microwave spectral imaging of an erupting magnetic flux rope: Implications for the standard solar flare model in three dimensions. Astrophys. J. Lett. 2020, vol. 895, p. L50. https://doi.org/10.3847/2041-8213/ab901a.
3. Fleishman G.D., Gary D.E., Chen B., et al. Decay of the coronal magnetic field can release sufficient energy to power a solar flare. Science. 2020, vol. 367, iss. 6475, pp. 278–280. https://doi.org/10.1126/science.aax6874.
4. Fleishman G.D., Nita G.M., Chen B., et al. Solar flare accelerates nearly all electrons in a large coronal volume. Nature. 2022, vol. 606, pp. 674–677. https://doi.org/10.1038/s41586-022-04728-8.
5. Gary D.E., Chen B., Dennis B.R., et al. Microwave and hard X-ray observations of the 2017 September 10 solar limb flare. Astrophys. J. 2018, vol. 863, no. 1, 9 p. https://doi.org/10.3847/1538-4357/aad0ef.
6. Melnikov V.F., Shibasaki K., Reznikova V.E. Loop top nonthermal microwave source in extended solar flaring loops. Astrophys. J. Lett. 2002, vol. 580, pp. 185–188.
7. Morgachev A.S., Kuznetsov S.A., Melnikov V.F. Radio diagnostics of the solar flaring loop parameters by direct fitting method. Geomagnetism and Aeronomy. 2014, vol. 54, iss. 7, pp. 933–942. https://doi.org/10.1134/S0016793214070081.
8. Morgachev A.S., Kuznetsov S.A., Melnikov V.F., Simoes J.A. Modeling the distribution of circular polarization degree of solar flare loops in event 19 July 2012. Geomagnetism and Aeronomy. 2015, vol. 55, iss. 8, pp. 1118–1123. https://doi.org/10.1134/S0016793215080228.
9. Shain A.V., Melnikov V.F., Morgachev A.S. The role of quasi-transverse propagation in observed polarization of flare loop microwave radiation. Geomagnetism and Aeronomy. 2017, vol. 57, pp. 988–995. https://doi.org/10.1134/S0016793217080217.
10. Smirnov D.A., Melnikov V.F. Microwave diagnostics of flare plasma by the direct fitting method based on data from the Siberian Radioheliograph. Sol.-Terr. Phys. 2024, vol. 10, iss. 3, pp. 25–36. https://doi.org/10.12737/stp-103202404.
11. Yan Y., Chen Z., Wang W., et al. Mingantu spectral radioheliograph for solar and space weather studies. Frontiers in Astronomy and Space Sciences. 2021, vol. 8, 584043. https://doi.org/10.3389/fspas.2021.584043.



