The Relationship between Long-Duration Gamma-Ray Flares and Solar Cosmic Rays

Abstract

A characteristic pattern of solar hard X-ray emission, first identified in SOL1969-03-30 by Frost & Dennis (1971), turns out to have a close association with the prolonged high-energy gamma-ray emission originally observed by Forrest et al. (1985). This identification has become clear via the observations of long-duration gamma-ray flares by the Fermi/LAT experiment, for example in the event SOL2014-09-01. The distinctive features of these events include flat hard X-ray spectra extending well above 100 keV, a characteristic pattern of time development, low-frequency gyrosynchrotron peaks, CME association, and gamma-rays identifiable with pion decay originating in GeV ions. The identification of these events with otherwise known solar structures nevertheless remains elusive, in spite of the wealth of EUV imagery available from SDO/AIA. The quandary is that these events have a clear association with SEPs in the high corona, and yet the gamma-ray production implicates the photosphere itself, despite the strong mirror force that should focus the particles \textit{away} from the Sun We discuss the morphology of these phenomena and propose a solution to this problem.

References in corpus (5)

• Big-Bang Nucleosynthesis
• Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares
• First detection of >100 MeV gamma rays associated with a behind-the-limb solar flare
• The magnetic connectivity of coronal shocks from behind-the-limb flares to the visible solar surface during $\gamma$-ray events
• Particle energisation in a collapsing magnetic trap model: the relativistic regime

Cited by in corpus (8)

• Extreme solar events
• Comparing Long-Duration Gamma-Ray Flares and High-Energy Solar Energetic Particles
• Radio, Hard X-Ray, and Gamma-Ray Emissions Associated with a Far-Side Solar Event
• Cosmic-Ray Interactions in the Solar Atmosphere
• Source of Energetic Protons in the 2014 September 1 Sustained Gamma-ray Emission Event
• FLUKA Simulations of Pion Decay Gamma-radiation from Energetic Flare Ions
• Always a Farm Boy
• Role of CME clusters and CME-CME interactions in producing sustained $\gamma$-ray emission