Local Acceleration of Multi‐MeV Electrons Inside Earth's Impenetrable Barrier During the May 2024 Superstorm
Year: 2026
Type: article
Abstract: The inner radiation belt ( L* < 3) has long been considered an impenetrable barrier to ultra‐relativistic electrons. Here we show that this barrier can be breached under extreme space weather conditions. Using continuous near‐equatorial observations from the Arase satellite, we show that the May 2024 superstorm rapidly generated multi‐MeV electrons deep inside the inner magnetosphere. Phase space density profiles reveal the development of a local maximum at L* ∼ 3, providing evidence that local in situ acceleration established multi‐MeV electron source before supplying inward and outward radial diffusion. Simultaneous observations of intense chorus waves under a strongly depleted plasma region, maintained by enhanced convection and a negative ionospheric storm, are consistent with chorus‐driven local acceleration. These findings demonstrate that local acceleration can establish a multi‐MeV electron source inside the impenetrable barrier under extreme space weather conditions.
Source: Geophysical Research Letters
DOI: 10.1029/2026gl125879
Institutions: Kyung Hee University, Institute for Space-Earth Environmental Research, Nagoya University, Kyoto University, Kanazawa University, National Institute of Information and Communications Technology, Okinawa Institute of Science and Technology Graduate University, GFZ Helmholtz Centre for Geosciences, Japan Aerospace Exploration Agency, Tohoku University, Kyushu Institute of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,190
OpenAlex ID: W7223672622