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Title: The extent of non-thermal particle acceleration in relativistic, electron-positron reconnection

Reconnection is studied as an explanation for high-energy flares from the Crab Nebula. The production of synchrotron emission >100 MeV challenges classical models of acceleration. 3D simulation shows that reconnection, converting magnetic energy to kinetic energy, can accelerate beyond γrad. The power-law index and high-energy cutoff are important for understanding the radiation spectrum dN/dγ = f(γ) ∝ γ. α and cutoff were measured vs. L and σ, where L is system (simulation) size and σ is upstream magnetization (σ = B2/4πnmc2). α can affect the high-energy cutoff. In conclusion, for collisionless relativistic reconnection in electron-positron plasma, without guide field, nb/nd=0.1: (1) relativistic magnetic reconnection yields power-law particle spectra, (2) the power law index decreases as σ increases, approaching ≈1.2. (3) the power law is cut off at an energy related to acceleration within a single current layer, which is proportional to the current layer length (for small systems, that length is the system length, yielding γc2 ≈ 0.1 L/ρ0; for large systems, the layer length is limited by secondary tearing instability, yielding γc1 ≈ 4σ; the transition from small to large is around L/ρ0 = 40σ.). (4) although the large-system energy cutoff is proportional to the average energy per particle,more » it is significantly higher than the average energy per particle.« less
 [1] ;  [2]
  1. University of Colorado
  2. Los Alamos National Laboratory
Publication Date:
OSTI Identifier:
Report Number(s):
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Resource Relation:
Conference: Plasma Energization: Exchanges between Fluid and Kinetic Scales ; 2015-05-04 - 2015-05-06 ; Los Alamos, New Mexico, United States
Research Org:
Los Alamos National Laboratory (LANL)
Sponsoring Org:
University of Colorado
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS Astronomy and Astrophysics