Solar flares as electron accelerators: toward a resolution of the acceleration efficiency issue
Fuente:
arXiv
Enregistré dans:
| Auteurs principaux: | , , , , |
|---|---|
| Format: | Preprint |
| Publié: |
2025
|
| Sujets: | |
| Accès en ligne: | |
| Tags: |
Ajouter un tag
Pas de tags, Soyez le premier à ajouter un tag!
|
| _version_ | 1866909482654629888 |
|---|---|
| author | Volpara, Anna Massa, Paolo Piana, Michele Massone, Anna Maria Emslie, A Gordon |
| author_facet | Volpara, Anna Massa, Paolo Piana, Michele Massone, Anna Maria Emslie, A Gordon |
| contents | A major open issue concerning the active Sun is the effectiveness with which magnetic reconnection accelerates electrons in flares. A paper published by {\em{Nature}} in 2022 used microwave observations to conclude that the Sun is an almost ideal accelerator, energizing nearly all electrons within a coronal volume to nonthermal energies. Shortly thereafter, a paper published in {\em{Astrophysical Journal Letters}} used hard X-ray measurements \emph{of the same event} to reach the contradictory conclusion that less than 1\% of the available electrons were accelerated. Here we address this controversy by using spatially resolved observations of hard X-ray emission and a spectral inversion method to determine the evolution of the electron spectrum throughout the flare. So we estimated the density of the medium where electrons accelerate and, from this, the ratio of accelerated to ambient electron densities. Results show that this ratio never exceeds a percent or so in the cases analyzed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_04769 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Solar flares as electron accelerators: toward a resolution of the acceleration efficiency issue Volpara, Anna Massa, Paolo Piana, Michele Massone, Anna Maria Emslie, A Gordon Solar and Stellar Astrophysics High Energy Astrophysical Phenomena Space Physics 85-08 A major open issue concerning the active Sun is the effectiveness with which magnetic reconnection accelerates electrons in flares. A paper published by {\em{Nature}} in 2022 used microwave observations to conclude that the Sun is an almost ideal accelerator, energizing nearly all electrons within a coronal volume to nonthermal energies. Shortly thereafter, a paper published in {\em{Astrophysical Journal Letters}} used hard X-ray measurements \emph{of the same event} to reach the contradictory conclusion that less than 1\% of the available electrons were accelerated. Here we address this controversy by using spatially resolved observations of hard X-ray emission and a spectral inversion method to determine the evolution of the electron spectrum throughout the flare. So we estimated the density of the medium where electrons accelerate and, from this, the ratio of accelerated to ambient electron densities. Results show that this ratio never exceeds a percent or so in the cases analyzed. |
| title | Solar flares as electron accelerators: toward a resolution of the acceleration efficiency issue |
| topic | Solar and Stellar Astrophysics High Energy Astrophysical Phenomena Space Physics 85-08 |
| url | https://arxiv.org/abs/2502.04769 |