title: Why does Steady-State Magnetic Reconnection have a Maximum Local Rate of Order 0.1?
abstract: Simulations suggest collisionless steady-state magnetic reconnection of Harris-type current sheets proceeds with a rate of order 0.1, independent of dissipation mechanism. We argue this long-standing puzzle is a result of constraints at the magnetohydrodynamic (MHD) scale. We predict the reconnection rate as a function of the opening angle made by the upstream magnetic fields, finding a maximum reconnection rate close to 0.2. The predictions compare favorably to particle-in-cell simulations of relativistic electron-positron and nonrelativistic electron-proton reconnection. The fact that simulated reconnection rates are close to the predicted maximum suggests reconnection proceeds near the most efficient state allowed at the MHD scale. The rate near the maximum is relatively insensitive to the opening angle, potentially explaining why reconnection has a similar fast rate in differing models.
authors.affiliation: NASA-Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Yi-Hsin
authors.initials: YH
authors.lastname: Liu
authors.affiliation: NASA-Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hesse
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: F
authors.initials: F
authors.lastname: Guo
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: W
authors.initials: W
authors.lastname: Daughton
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: West Virginia University, Morgantown, West Virginia 26506, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Cassak
authors.affiliation: University of Delaware, Newark, Delaware 19716, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Shay