Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

J. Egedal , A. Le , W. Daughton , B. Wetherton , P. A. Cassak , L. -J. Chen , B. Lavraud (1) , R. B. Torbert , J. Dorelli , D. J. Gershman , L. A. Avanov

1 IRAP - Institut de recherche en astrophysique et planétologie

Supported by a kinetic simulation, we derive an exclusion energy parameter E_X providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell demon, only high-energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low-density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low-density separatrix.

Keywords: Physics - Plasma Physics

Domains: Sciences of the Universe [physics]

J. Egedal, A. Le, W. Daughton, B. Wetherton, P. A. Cassak, et al.. Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection. Physical Review Letters, 2016, 117, ⟨10.1103/PhysRevLett.117.185101⟩. ⟨insu-03669409⟩