TeV Solar Gamma Rays From Cosmic-Ray Interactions

Abstract

The Sun is a bright source of GeV gamma rays, due to cosmic rays interacting with solar matter and photons. Key aspects of the underlying processes remain mysterious. The emission in the TeV range, for which there are neither observational nor theoretical studies, could provide crucial clues. The new experiments HAWC (running) and LHAASO (planned) can look at the Sun with unprecedented sensitivity. In this paper, we predict the very high-energy (up to 1000 TeV) gamma-ray flux from the solar disk and halo, due to cosmic-ray hadrons and electrons ($e^{+}+e^{-}$), respectively. We neglect solar magnetic effects, which is valid at TeV energies; at lower energies, this gives a theoretical lower bound on the disk flux and a theoretical upper bound on the halo flux. We show that the solar-halo gamma-ray flux allows the first test of the $\sim 5$--70 TeV cosmic-ray electron spectrum. Further, we show that HAWC can immediately make an even stronger test with nondirectional observations of cosmic-ray electrons. Together, these gamma-ray and electron studies will provide new insights about the local density of cosmic rays and their interactions with the Sun and its magnetic environment. These studies will also be an important input to tests of new physics, including dark matter.

Main text 9 pages, 6 figures; minor changes; conclusions unchanged; matches published version

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Cited by in corpus (31)

• Powerful Solar Signatures of Long-Lived Dark Mediators
• Solar Atmospheric Neutrinos: A New Neutrino Floor for Dark Matter Searches
• Constraints on Spin-Dependent Dark Matter Scattering with Long-Lived Mediators from TeV Observations of the Sun with HAWC
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• Evidence for a New Component of High-Energy Solar Gamma-Ray Production
• Unexpected Dip in the Solar Gamma-Ray Spectrum
• Cosmic-ray interactions with the Sun using the FLUKA code
• The Southern Wide-Field Gamma-Ray Observatory (SWGO): A Next-Generation Ground-Based Survey Instrument for VHE Gamma-Ray Astronomy
• First HAWC Observations of the Sun Constrain Steady TeV Gamma-Ray Emission
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• Solar constraints on captured electrophilic dark matter
• StellarICS: Inverse Compton Emission from the Quiet Sun and Stars from keV to TeV
• On the expected $\gamma$-ray emission from nearby flaring stars
• A Solar System Test of Self-Interacting Dark Matter
• Searches for neutrinos from cosmic-ray interactions in the Sun using seven years of IceCube data
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• Search for gamma-ray emission from the Sun during solar minimum with the ARGO-YBJ experiment
• Small-Scale Magnetic Fields are Critical to Shaping Solar Gamma-Ray Emission
• Yet Another Sunshine Mystery: Unexpected Asymmetry in GeV Emission from the Solar Disk
• The prediction of using LHAASO's cosmic-ray electron measurements to constrain decaying heavy dark matter
• Role of magnetic arcades in explaining the puzzle of the gamma-ray emission from the solar disk
• Anisotropic Photon and Electron Scattering without Ultrarelativistic Approximation
• Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields
• Puzzling Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi-LAT
• Search for spatial coincidence between IceCube neutrinos and gamma-ray bright red dwarfs
• Angular Distribution of Gamma Rays Produced in Proton-Proton Collisions
• First Observations of Solar Halo Gamma Rays Over a Full Solar Cycle
• Search for MeV Gamma-ray emission from TeV bright red dwarfs with COMPTEL