Observational Evidence for Stochastic Shock Drift Acceleration of Electrons at the Earth's Bow Shock

Abstract

The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale (MMS) observations at Earth's bow shock. The theoretical model can explain electron acceleration to mildly relativistic energies at high-speed astrophysical shocks, which may provide a solution to the long-standing issue of electron injection.

7 pages, 4 figures. Published in PRL

References in corpus (5)

• Electron Surfing and Drift Accelerations in a Weibel-dominated High-Mach-number Shock
• Relativistic electrons produced by foreshock disturbances
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• Non-linear diffusive shock acceleration: A recipe for injection of electrons
• Revealing an unexpectedly low electron injection threshold via reinforced shock acceleration
• Electron acceleration at supernova remnants
• Direct observations of cross-scale energy transfer in space plasmas
• Intense whistler-mode waves at foreshock transients: characteristics and regimes of wave-particle resonant interaction
• Mach Number Dependence of Ion-scale Kinetic Instability at Collisionless Perpendicular Shock: Condition for Weibel-dominated Shock
• In-situ Measurement of the Energy Fraction in Supra-thermal and Energetic Particles at ACE, Wind, and PSP Interplanetary Shocks
• Parallel Velocity Mixing Yielding Enhanced Electron Heating During Magnetic Pumping
• Electron shock drift acceleration at a low-Mach-number, low-plasma-beta quasi-perpendicular shock
• Electron Energization in Quasi-Parallel Shocks: Test-Particle-Electrons in a Proton Driven Turbulence
• Multi-Mission Observations of Relativistic Electrons and High-Speed Jets Linked to Shock Generated Transients
• Electron Heating in 2D Particle-in-Cell Simulations of Quasi-Perpendicular Low-Beta Shocks
• Electron-Ion Temperature Ratio in Transrelativistic Unmagnetized Shock Waves
• Detailed characterization of laboratory magnetized super-critical collisionless shock and of the associated proton energization
• Current sheets, plasmoids and flux ropes in the heliosphere. Part II: Theoretical aspects
• The electron foreshock at high-Mach-number nonrelativistic oblique shocks
• Transport of electrons in tangled magnetic fields