Exploring the Origin of Solar Energetic Electrons II: Investigating Turbulent Coronal Acceleration
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912247857545216 |
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| author | Pallister, Ross Jeffrey, Natasha L. S. Stores, Morgan |
| author_facet | Pallister, Ross Jeffrey, Natasha L. S. Stores, Morgan |
| contents | Non-thermal particle acceleration in the solar corona is evident from both remote hard X-ray (HXR) sources in the chromosphere and direct in-situ detection in the heliosphere. Correlation of spectral indices between remote and in-situ energy spectra presents the possibility of a common source acceleration region within the corona, however the properties and location of this region are not well constrained. To investigate this we perform a parameter study for both the properties of the ambient plasma of a simulated acceleration region and the turbulent acceleration profile acting on an initially isotropic thermal electron population. We find that the independently varying the turbulent acceleration timescale $τ_{acc}$, acceleration profile standard deviation $σ$ and acceleration region length L result in in-situ spectral index variation of between 0.5 and 2.0 at 1.0 AU for < 100 keV electrons. Short timescale turbulent scattering in the flaring corona steepens the spectra by $\sim$ 0.5. It was also found that the in-situ spectral index $δ$ derived from the peak electron flux produces a spectral index $\sim$ 1.6 harder than that from a full-flare X-ray photon flux (of spectral index $γ$) simulated with the same intermediate parameters. Previous studies have indicated an approximate $δ\approx γ$ relationship for selected flares with measured in-situ electron and X-ray photon observations, suggesting that an extended source region with non-uniform plasma and/or acceleration properties may be necessary to reproduce this relationship. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_19105 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Exploring the Origin of Solar Energetic Electrons II: Investigating Turbulent Coronal Acceleration Pallister, Ross Jeffrey, Natasha L. S. Stores, Morgan Solar and Stellar Astrophysics High Energy Astrophysical Phenomena Non-thermal particle acceleration in the solar corona is evident from both remote hard X-ray (HXR) sources in the chromosphere and direct in-situ detection in the heliosphere. Correlation of spectral indices between remote and in-situ energy spectra presents the possibility of a common source acceleration region within the corona, however the properties and location of this region are not well constrained. To investigate this we perform a parameter study for both the properties of the ambient plasma of a simulated acceleration region and the turbulent acceleration profile acting on an initially isotropic thermal electron population. We find that the independently varying the turbulent acceleration timescale $τ_{acc}$, acceleration profile standard deviation $σ$ and acceleration region length L result in in-situ spectral index variation of between 0.5 and 2.0 at 1.0 AU for < 100 keV electrons. Short timescale turbulent scattering in the flaring corona steepens the spectra by $\sim$ 0.5. It was also found that the in-situ spectral index $δ$ derived from the peak electron flux produces a spectral index $\sim$ 1.6 harder than that from a full-flare X-ray photon flux (of spectral index $γ$) simulated with the same intermediate parameters. Previous studies have indicated an approximate $δ\approx γ$ relationship for selected flares with measured in-situ electron and X-ray photon observations, suggesting that an extended source region with non-uniform plasma and/or acceleration properties may be necessary to reproduce this relationship. |
| title | Exploring the Origin of Solar Energetic Electrons II: Investigating Turbulent Coronal Acceleration |
| topic | Solar and Stellar Astrophysics High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2502.19105 |