Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the Sun

Abstract

We analyze the Sun's shadow observed with the Tibet-III air shower array and find that the shadow's center deviates northward (southward) from the optical solar disc center in the "Away" ("Toward") IMF sector. By comparing with numerical simulations based on the solar magnetic field model, we find that the average IMF strength in the "Away" ("Toward") sector is $1.54\pm 0.21_{\mathrm{stat}}\pm 0.20_{\mathrm{syst}}$ ($1.62\pm 0.15_{\mathrm{stat}}\pm 0.22_{\mathrm{syst}}$) times larger than the model prediction. These demonstrate that the observed Sun's shadow is a useful tool for the quantitative evaluation of the average solar magnetic field.

7 pages, 4 figures

Cited by in corpus (5)

• The TeV Sun Rises: Discovery of Gamma rays from the Quiescent Sun with HAWC
• The Sun at GeV--TeV Energies: A New Laboratory for Astroparticle Physics
• Detectability of southern gamma-ray sources beyond 100 TeV with ALPAQUITA, the prototype experiment of ALPACA
• Role of magnetic arcades in explaining the puzzle of the gamma-ray emission from the solar disk
• Monitoring the daily variation of Sun-Earth magnetic fields using galactic cosmic rays