Electron-only magnetic reconnection in plasma turbulence

Matteo Faganello
Aix-Marseille University, CNRS, PIIM UMR 7345, Centre de Saint-Jérome, Avenue Escadrille Normandie Nièmen 13397 Marseille, France
Recently MMS satellites measured a turbulent regime in the solar wind plasma, downstream of the Earth's bow shock, where magnetic reconnection acting in all the observed current sheets (at the electron skin depth scale) is completely ruled by electrons. These ``electron-only'' reconnection events are characterized by electron jets unaccompanied by ion outflows, contrary to the standard picture of magnetic reconnection. Hybrid-Vlasov-Maxwell simulations of magnetized plasma turbulence, including non-linear electron inertia effects in the generalized Ohm.s law, are able to reproduce this behavior as soon as the fluctuation energy is injected at scales close the ion-kinetic scales. In this case ions turn out to be de-magnetized over the whole numerical domain while electrons follow a nearly electron-magnetohydrodynamic evolution leading to electron-only reconnection. The injection scale seems to be the control parameter of this behavior: if energy is injected at larger scales ion outflows do form in reconnecting sheets.