Solar-Terrestrial Physics Solar-Terrestrial Physics Solar-Terrestrial Physics 2500-0535 122599 10.12737/stp-122202612 ahzuiw Results of current research Results of current research Results of current research Possible errors in radio source parameters recovered by the fitting method related to anisotropy of the electron distribution Possible errors in radio source parameters recovered by the fitting method related to anisotropy of the electron distribution Смирнов Дмитрий Александрович Smirnov Dmitriy Aleksandrovich dmitriy.smirnov@unn.ru Мельников Виктор Федорович Melnikov Viktor Fedorovich v.melnikov@gaoran.ru

доктор физико-математических наук;

doctor of physical and mathematical sciences;

 Главная (Пулковская) астрономическая обсерватория РАН Санкт-Петербург Россия Central Astronomical Observatory at Pulkovo of RAS St. Petersburg Russian Federation Главная (Пулковская) астрономическая обсерватория РАН Санкт-Петербург Россия Central Astronomical Observatory at Pulkovo of RAS St. Petersburg Russian Federation 12 2 109 113 14 11 2025 03 03 2026 https://naukaru.ru/en/nauka/article/122599/view

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.

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 solar flares radioheliograph radio diagnostics The work was financially supported by RSF (grant No. 22-12-00308–P) The work was financially supported by RSF (grant No. 22-12-00308–P)

Altyntsev A.T., Lesovoi S.V., Globa М.V., et al. Multiwave Siberian Radioheliograph. Sol.-Terr. Phys. 2020, vol. 6, iss. 2, pp. 30–40. https://doi.org/10.12737/stp-62202003. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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.