The Mechanism of Electron Injection and Acceleration in Transrelativistic Reconnection
AffiliationUniv Arizona, Dept Astron
Univ Arizona, Steward Observ
radiation mechanisms: nonthermal
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationDavid Ball et al 2019 ApJ 884 57
RightsCopyright © 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractElectron acceleration during magnetic reconnection is thought to play a key role in time-variable high-energy emission from astrophysical systems. By means of particle-in-cell simulations of transrelativistic reconnection, we investigate electron injection and acceleration mechanisms in low-β electron–proton plasmas. We set up a diversity of density and field structures (e.g., X-points and plasmoids) by varying the guide field strength and choosing whether to trigger reconnection or let it spontaneously evolve. We show that the number of X-points and plasmoids controls the efficiency of electron acceleration, with more X-points leading to a higher efficiency. Using on-the-fly acceleration diagnostics, we also show that the nonideal electric fields associated with X-points play a critical role in the first stages of electron acceleration. As a further diagnostic, we include two populations of test particles that selectively experience only certain components of electric fields. We find that the out-of-plane component of the parallel electric field determines the hardness of the high-energy tail of the electron energy distribution. These results further our understanding of electron acceleration in this regime of magnetic reconnection and have implications for realistic models of black hole accretion flows.
VersionFinal published version
SponsorsNational Science Foundation (NSF) [AST-1715061, ACI1657507]; Chandra award [TM6-17006X]; United States Department of Energy (DOE) [DE-SC0016542]; National Aeronautics & Space Administration (NASA) [NNX-17AG21G]