Gamma Radiation from Flare-Accelerated Particles Impacting the Sun

Share, G. H.; Murphy, R. J.

doi:10.1029/165gm17

Cited by 8 publications

(6 citation statements)

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“…in agreement with measurements of the Ne/O abundance ratio in the corona [52]. For the 19 SMM flares measured before the launch of RHESSI, the average spectral index was around −4.3; however, the events observed with RHESSI tend to have much harder (flatter) slopes [7,12]. Even though most of the energy contained in ions resides in protons and a-particles, the abundances of heavier accelerated ions also provide constraints for acceleration processes.…”

Section: (B) Ion Energy Spectra Numbers and Abundances In Flaressupporting

confidence: 81%

“…However, for flare particles to escape into interplanetary space, they must have access to such lines. Radio observations (figures [11][12][13] show that electrons have access to field lines connecting at least the acceleration region to the low corona and, in some cases, even to the heliosphere. As shown in figure 13, the access to heliospheric lines may evolve during a flare.…”

Section: (B) Electron Injection From the Flare Site To The Interplanementioning

confidence: 99%

“…This continuum (curves 3 and 5) is dominant below 1 MeV and again in the 10-50 MeV range. Energetic ions with energies in the more than 1 MeV per nuc to 100 MeV per nuc range produce, through interactions in the solar atmosphere, a complete g-ray line spectrum (curve 4), which consists of several nuclear de-excitation lines, neutron capture and positron annihilation lines (for reviews, see [11][12][13]). When ions over a few hundred MeV per nuc are produced in the flare, nuclear interactions with the ambient medium produce secondary pions whose decay produces a broadband continuum at photon energies above 10 MeV (with a broad peak around 70 MeV from neutral pion radiation; curve 6) and also secondary neutrons which, if energetic enough, may escape from the Sun and be directly detected in interplanetary space or at ground level (respectively, more than 10 MeV or 200 MeV neutrons; for a review, see [14]).…”

Section: Hard X-ray and G-ray Diagnostics Of Flare Energetic Particlesmentioning

confidence: 99%

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Solar flares and energetic particles

Vilmer

2012

Phil. Trans. R. Soc. A.

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Solar flares are now observed at all wavelengths from g-rays to decametre radio waves. They are commonly associated with efficient production of energetic particles at all energies. These particles play a major role in the active Sun because they contain a large amount of the energy released during flares. Energetic electrons and ions interact with the solar atmosphere and produce high-energy X-rays and g-rays. Energetic particles can also escape to the corona and interplanetary medium, produce radio emissions (electrons) and may eventually reach the Earth's orbit. I shall review here the available information on energetic particles provided by X-ray/g-ray observations, with particular emphasis on the results obtained recently by the mission Reuven Ramaty High-Energy Solar Spectroscopic Imager. I shall also illustrate how radio observations contribute to our understanding of the electron acceleration sites and to our knowledge on the origin and propagation of energetic particles in the interplanetary medium. I shall finally briefly review some recent progress in the theories of particle acceleration in solar flares and comment on the still challenging issue of connecting particle acceleration processes to the topology of the complex magnetic structures present in the corona.

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Section: (B) Ion Energy Spectra Numbers and Abundances In Flaressupporting

confidence: 81%

Section: (B) Electron Injection From the Flare Site To The Interplanementioning

confidence: 99%

Section: Hard X-ray and G-ray Diagnostics Of Flare Energetic Particlesmentioning

confidence: 99%

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Solar flares and energetic particles

Vilmer

2012

Phil. Trans. R. Soc. A.

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“…Accelerated ions are even less well understood than electrons due to the difficulties encountered in observing their γ-ray emission. Accelerated ions in the range of 1-100 MeV/nucleon can be detected via various γ-ray lines in the range of 1-10 MeV due to nuclear de-excitation, neutron capture, and positron annihilation [7][8][9][10][11][12][13][14]. Accelerated ions with energies greater than 100 MeV/nucleon can be detected via the decay of secondary pions via nuclear reactions with the ambient medium.…”

Section: Scientific Objectivesmentioning

confidence: 99%

The Solar Particle Acceleration Radiation and Kinetics (SPARK) Mission Concept

Reid,

Musset,

Ryan

et al. 2023

Aerospace

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Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure.

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“…The picture for flare ions remains less complete, partly because flares producing detectable γ-rays are much rarer but also because of the greater complexity of the nuclear radiation mechanisms. Ion acceleration in flares is studied via a variety of signatures at γ-ray wavelengths, consequences of nuclear reactions of primary accelerated ions with ambient nuclei (Share and Murphy, 2006;Murphy et al, 2007;Vilmer, MacKinnon, and Hurford, 2011): nuclear de-excitation lines in the 0.4 − 7 MeV range, excited by ions of 1 − 100 MeV/nucleon (Ramaty, Kozlovsky, and Lingenfelter, 1979;Kozlovsky, Murphy, and Ramaty, 2002); 2.223 MeV neutron capture and 511 keV positron annihilation lines, each resulting from ions spanning a wide energy range, from a few to 100s of MeV/nucleon (Lockwood, Debrunner, and Ryan, 1997;Hua et al, 2002;Kozlovsky, Lingenfelter, and Ramaty, 1987;Kozlovsky, Murphy, and Ramaty, 2002;Murphy et al, 2007); continuum radiation in the 0.1 MeV range, resulting from pion decay products of 0.2 − 0.3 GeV/nucleon ions (Dermer, 1986b;Murphy, Dermer, and Ramaty, 1987;Mandzhavidze and Ramaty, 1992;Vilmer et al, 2003). Energetic neutrons detected in space or with ground-based instruments also give information on accelerated flare ions (Chupp et al, 1987;Kocharov et al, 1998;Watanabe et al, 2006, e.g.…”

Section: Introductionmentioning

confidence: 99%

Self-consistent Modelling of Gamma-Ray Spectra from Solar Flares with the Monte Carlo Simulation Package FLUKA

Tusnski,

Szpigel,

de Castro

et al. 2019

Preprint

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We use the Monte Carlo particle physics code FLUKA (Fluktuierende Kaskade) to calculate γ-ray spectra expected from solar flare energetic ion distributions. The FLUKA code includes robust physics-based models for electromagnetic, hadronic and nuclear interactions, sufficiently detailed for it to be a useful tool for calculating nuclear de-excitation, positron annihilation and neutron capture line fluxes and shapes, as well as ≈ GeV continuum radiation from pion decay products. We show nuclear de-excitation γ-ray line model spectra from a range of assumed primary accelerated ion distributions and find them to be in good agreement with those found using the code of Murphy et al. (2009). We also show full γ-ray model spectra which exhibit all the typical structures of γ-ray spectra S. Szpigel

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Gamma Radiation from Flare-Accelerated Particles Impacting the Sun

Cited by 8 publications

References 54 publications

Solar flares and energetic particles

Solar flares and energetic particles

The Solar Particle Acceleration Radiation and Kinetics (SPARK) Mission Concept

Self-consistent Modelling of Gamma-Ray Spectra from Solar Flares with the Monte Carlo Simulation Package FLUKA

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