Cosmic-Ray Interactions in the Solar Atmosphere

Abstract

High-energy particles enter the solar atmosphere from Galactic or solar coronal sources, producing an "albedo'' source from the quiet Sun, now observable across a wide range of photon energies. The interaction of high-energy particles in a stellar atmosphere depends essentially upon the joint variation of the magnetic field and the gas, which heretofore has been characterized parametrically as P ~ B^alpha with P the gas pressure and B the magnitude of the magnetic field. We re-examine that parametrization by using a self-consistent 3D MHD model (Bifrost) and show that this relationship tends to P ~ B^{2.9+-0.1} based on the visible portions of the sample of open-field flux tubes in such a model, but with large variations from point to point. This scatter corresponds to the strong meandering of the open-field flux tubes in the lower atmosphere, which will have a strong effect on the prediction of the emission anisotropy (limb brightening). The simulations show that much of the open flux in coronal holes originates in weak-field regions within the granular pattern of the convective motions seen in the simulations.

arXiv commentPreprint prepared for submission to MNRAS

References in corpus (13)

• Solar Modulation of Cosmic Rays
• The stellar atmosphere simulation code Bifrost
• A publicly available simulation of an enhanced network region of the Sun
• Fermi-LAT Observations of Two Gamma-Ray Emission Components from the Quiescent Sun
• High-Energy Gamma-Ray Emission From Solar Flares: Summary of Fermi LAT Detections and Analysis of Two M-Class Flares
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• Fermi Large Area Telescope Observations of the Cosmic-Ray Induced gamma-ray Emission of the Earth's Atmosphere
• Fermi-LAT observations of the 2017 September 10${}^{th}$ solar flare
• Probing the Puzzle of Behind-the-Limb $\gamma$-ray Flares: Data-driven Simulations of Magnetic Connectivity and CME-driven Shock Evolution
• The Relationship between Long-Duration Gamma-Ray Flares and Solar Cosmic Rays
• Jupiter as a Giant Cosmic Ray Detector
• Coronal radiation belts

Cited by in corpus (10)

• Stellar Superflares Observed Simultaneously with Kepler and XMM-Newton
• The Poissonian Origin of Power Laws in Solar Flare Waiting Time Distributions
• The Solar Memory From Hours to Decades
• On the Impulsive Heating of Quiet Solar Corona
• FLUKA Simulations of Pion Decay Gamma-radiation from Energetic Flare Ions
• A New Component from the Quiet Sun: Synchrotron Radiation from Galactic Cosmic-Ray Electrons
• Small-Scale Magnetic Fields are Critical to Shaping Solar Gamma-Ray Emission
• Puzzling Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi-LAT
• Angular Distribution of Gamma Rays Produced in Proton-Proton Collisions
• First Observations of Solar Halo Gamma Rays Over a Full Solar Cycle