Implications of X-ray Observations for Electron Acceleration and Propagation in Solar Flares

By Gordon D. Holman, Markus J. Aschwanden, Henry Aurass, Marina Battaglia, P. Grigis, E. P. Kontar, Wei Liu, P. Saint-Hilaire, V. V. Zharkova. 2011

305 citations recorded by the source corpus.

High-energy X-rays and γ-rays from solar flares were discovered just over fifty years ago. Since that time, the standard for the interpretation of spatially integrated flare X-ray spectra at energies above several tens of keV has been the collisional thick-target model. After the launch of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in early 2002, X-ray spectra and images have been of sufficient quality to allow a greater focus on the energetic electrons responsible for the X-ray emission, including their origin and their interactions with the flare plasma and magnetic field. The result has been new insights into the flaring process, as well as more quantitative models for both electron acceleration and propagation, and for the flare environment with which the electrons interact. In this article we review our current understanding of electron acceleration, energy loss, and propagation in flares. Implications of these new results for the collisional thick-target model, for general flare models, and for future flare studies are discussed.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/3bcc156868fcd8ecae430e1a63480be2c2cea0c2

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In Astronomy and Astrophysics

1. M. Temmer
2. H. Hudson
3. V. Petrosian
4. Wei Liu
5. Brian R. Dennis
6. L. Fletcher
7. S. Krucker
8. Astrid Veronig

In Geophysics

1. M. Temmer
2. H. Hudson
3. Michele Piana

Citations in the corpus

• The Spectrometer/Telescope for Imaging X-rays (STIX) (2020, background): “Hence, hard X-ray emissions provide ideal diagnostics of the hottest plasmas in solar flares and of the nonthermal tails seen at energies above the hottest thermal population (for reviews see Fletcher et al. 2011, Holman et al. 2011, Kontar et al. 2011).”
• A review of solar type III radio bursts (2014, background): “Bremsstrahlung X-rays are emitted (see Holman et al., 2011, as a recent review) and are detected both directly and through X-rays reflected from the solar surface (e.g. Kontar & Jeffrey, 2010).”
• Deducing Electron Properties from Hard X-ray Observations (2011, background): “Thus, the determination of Ec plays a key role in the interpretation of hard X-ray data (see also Holman et al. 2011, this issue).”
• Recent Advances in Understanding Particle Acceleration Processes in Solar Flares (2011, background): “The spectral index difference∆γ = 2.0 predicted (Brown 1971) between thinand (collision-dominated) thick-target sources isnot observed in most cases (Holman et al. 2011).”
• An Observational Overview of Solar Flares (2011, background): “Accelerated Electrons:The energy in accelerated electrons can be determined from applying a thick-target model see (see Holman et al. 2011) to the measured HXR spectrum in order to obtain the injected spectrumF0(E0) (electrons s−1 keV−1) and calculating the corresponding injected power from Ue =…”