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Revealing an unexpectedly low electron injection threshold via reinforced shock acceleration
Savvas Raptis1, Ahmad Lalti2,3,4, Martin Lindberg5,6
1Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA. savvas.raptis@jhuapl.edu.
Nature Communications
|January 13, 2025
Summary
Collisionless shock waves accelerate relativistic electrons through a reinforced model. This study reveals how these powerful natural accelerators consistently energize electrons to very high energies, explaining cosmic ray origins.
Area of Science:
- Plasma Physics
- Astrophysics
- Particle Acceleration
Background:
- Collisionless shock waves are potent particle accelerators found across diverse cosmic and laboratory environments.
- Understanding the mechanisms behind relativistic electron acceleration in these shocks is crucial for astrophysics and cosmic ray studies.
Purpose of the Study:
- To develop and validate a reinforced model for relativistic electron acceleration at collisionless shocks.
- To investigate the role of transient structures, wave-particle interactions, and variable stellar wind conditions in particle energization.
Main Methods:
- Combined in-situ satellite measurements with advanced theoretical developments.
- Incorporated multiscale processes including transient structures and wave-particle interactions into the acceleration model.
Main Results:
- Established an electron injection threshold within the suprathermal energy range, achievable through various plasma phenomena.
- Demonstrated that typical shocks can consistently accelerate electrons to relativistic energies.
- The reinforced model successfully explains the origin of electron cosmic rays.
Conclusions:
- The developed model provides a refined understanding of particle acceleration at collisionless shocks.
- This research offers significant insights into the origins of high-energy electron cosmic rays.
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