12-20 July 2017
Asia/Seoul timezone
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BEXCO - Room F(201/202/203/204)

[GA244] Cosmic rays and their modulation in the inner heliosphere by looking at the gamma-ray sun


  • Elena ORLANDO

Primary authors



Galactic Cosmic Rays (CRs) can reach the Sun, and this is proven by looking at the quiescent solar gamma-ray emission up to GeV energies. Measurements of high-energy Galactic CRs in the inner heliosphere close to the Sun have never been performed, hence studying the gamma-ray emission close to the Sun indirectly informs us about CRs in this region. The solar gamma-ray steady state was first detected by EGRET and now by Fermi LAT with high significance. Characterized by two distinct emissions, it is unique for its spatially and spectrally distinct components: 1) disc emission due by pion decay of CR hadrons interacting with the solar atmosphere; 2) spatially extended emission from inverse Compton (IC) scattering of CR electrons on the solar photons of the heliosphere. Being produced by CRs, which are affected by solar modulation, the intensity of both emissions is expected to be inversely proportional to the solar activity. We present updates on solar IC models based on available CR measurements for different solar activities. We also discuss the importance for present and future missions.