Ultra-relativistic Electron Acceleration during High-intensity Long-duration Continuous Auroral Electrojet Activity Events

• Published in: The Astrophysical journal Vol. 965; no. 2; pp. 146 - 157
• Main Authors: Hajra, Rajkumar, Tsurutani, Bruce T., Lu, Quanming, Lakhina, Gurbax S., Du, Aimin, Echer, Ezequiel, Franco, Adriane M. S., Bolzan, Mauricio J. A., Gao, Xinliang
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-04-2024; IOP Publishing
• Subjects: Auroral electrojet; Auroral electrojets; Chorus waves; Convection; Coronal holes; Electrojets; Electron acceleration; Electrons; Interplanetary magnetic fields; Interplanetary medium; Magnetospheres; Particle interactions; Relativistic effects; Solar activity; Solar corona; Solar coronal mass ejections; Solar storm; Solar wind; Van Allen radiation belts
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad2dfe

Abstract
Magnetospheric relativistic electrons are accelerated during substorms and strong convection events that occur during high-intensity long-duration continuous auroral electrojet activity (HILDCAA) events, associated with solar wind high-speed streams (coming from coronal holes). From an analysis of ∼2–20 MeV electrons at
L
∼ 2–7 measured by the Van Allen Probe satellite, it is shown that ∼3.4–4.1 days long HILDCAA events are characterized by ∼7.2 MeV electron acceleration in the
L
∼ 4.0–6.0 region, which occurs ∼2.9–3.4 days after the onset of HILDCAA. The dominant acceleration process is due to wave–particle interactions between magnetospheric electromagnetic chorus waves and substorm-injected ∼100 keV electrons. The longer the HILDCAA and chorus last, the higher the maximum energy of the accelerated relativistic electrons. The acceleration to higher and higher energies is due to a bootstrap mechanism.