Multiscale and multidimensional modeling of particle acceleration and transport in solar flares

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Abstract
Multi-messenger, multi-viewpoint, and time-resolved observations of solar flares are now providing unprecedented constraints on particle acceleration sites, energy conversion, and energy transport. The interpretation of current observations, including microwave imaging spectroscopy from EOVSA, hard x-ray (HXR) imaging from Solar Orbiter/STIX, gamma-ray diagnostics from Fermi, and in situ measurements from Parker Solar Probe and Solar Orbiter, collectively demands modeling frameworks that go beyond traditional spatially unresolved, one-zone models or single-mechanism descriptions. This review surveys multiscale and multidimensional modeling approaches, including kinetic, magnetohydrodynamic (MHD), and macroscopic particle models, that are being developed to meet the need. Kinetic simulations reveal that three-dimensional (3D) effects, including field-line chaos and self-generated turbulence, are essential for sustained power-law particle acceleration. MHD simulations now capture flux-rope eruptions, plasmoid-unstable current sheets, and turbulent flare regions in realistic magnetic topologies. Macroscopic models coupling MHD with energetic-particle models produce spatially resolved electron distributions and synthetic HXR and microwave emissions for direct comparison with observations. Despite these advances, outstanding challenges remain in bridging kinetic and global scales, improving MHD simulations and macroscopic particle models, and achieving quantitative model-observation closure.
Funding Information
  • NASA Headquarters (NNH240B72A)
  • National Science Foundation (AST-2107745)
  • National Science Foundation (AGS-2334930)
  • NASA Headquarters (80NSSC21K1313)
  • University of California Berkeley (00011753)
  • Smithsonian Astrophysical Observatory (SV1-21012)
  • NASA Headquarters (80NSSC20K1318)
  • National Science Foundation (AST-2108853)
  • National Science Foundation (AGS-2334931)
  • Laboratory Directed Research and Development (20260244ER)
  • National Energy Research Scientific Computing Center (FES-ERCAP0033004)

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