Sun as a cosmic ray TeVatron

Understand

Very recently, HAWC observatory discovered the high-energy gamma ray emission from the solar disk during the quiescent stage of the Sun, extending the Fermi-LAT detection of intense, hard emission between 0.1 - 200 GeV to TeV energies.

• The flux of these observed gamma-rays is significantly higher than that theoretically expected from hadronic interactions of galactic cosmic rays with the solar atmosphere.
• More importantly, spectral slope of Fermi and HAWC observed gamma ray energy spectra differ significantly from that of galactic cosmic rays casting doubt on the prevailing galactic cosmic ray ancestry model of solar disk gamma rays.
• In this work, we argue that the quiet Sun can accelerate cosmic rays to TeV energies with an appropriate flux level in the solar chromosphere, as the solar chromosphere in its quiet state probably possesses the required characteristics to accelerate cosmic rays to TeV energies.