2018/07/01 by I. M. Chertok
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Earthquake Detection and Analysis #Flare #Flux (metallurgy) #Microwave #Particle acceleration #Proton #Radio spectrum #Solar and Space Plasma Dynamics #Solar energetic particles #Solar flare #Spectral index #Spectral line #astro-ph.SR
paper · pdf · doi:10.1134/s0016793218040035
published as Geomagnetism and Aeronomy, 2018, Vol. 58, No. 4, pp. 457-463 · 10 pages, 2 figures
openalex publication_date 2018/07/01 · arxiv created 2018/08/15 · arxiv updated 2018/08/16 · openalex created_date 2018/08/22 · openalex updated_date 2026/08/05
The powerful solar flares that occurred on September 4–10, 2017 are analyzed based on a quantitative diagnostics method for proton flares developed at the Institute of Terrestrial Magnetism, the Ionosphere and Radio-Wave Propagation (IZMIRAN) in the 1970–1980s. We show that the fluxes and energy spectra of the protons reached the Earth with the energies of tens of MeV qualitatively and quantitatively correspond to the intensity and frequency spectra of the microwave radio bursts in the range of 2.7–15.4 GHz. Specifically, the flare of September 4 with a peak radio flux S ~ 2000 sfu at the frequency f ~ 3 GHz (i.e., with the soft radio spectrum) was accompanied by a significant proton flux J (>10 MeV) ~100 pfu and a soft energy spectrum with the index γ ~3.0, while the strong flare on September 10 with S ~ 21000 sfu at f ~ 15 GHz (i.e., with the hard radio spectrum) led to a very intense proton event with J (>10 MeV) ~1000 pfu with a hard spectrum (γ ~ 1.4), including the ground level enhancement (GLE72). This is further evidence that microwave radio data can be successfully used in diagnostics of proton flares independently of a specific source of particle acceleration at the Sun, in particular, with the IZMIRAN method.