Abstract We report on the observations of an electron vortex magnetic hole corresponding to a new type of coherent structure in the turbulent magnetosheath plasma using the Magnetospheric Multiscale mission data. The magnetic hole is characterized by a magnetic depression, a density peak, a total electron temperature increase (with a parallel temperature decrease but a perpendicular temperature increase), and strong currents carried by the electrons. The current has a dip in the core region and a peak in the outer region of the magnetic hole. The estimated size of the magnetic hole is about 0.23 ρ i (∼30 ρ e) in the quasi-circular cross-section perpendicular to its axis, where ρ i and ρ e are respectively the proton and electron gyroradius. There are no clear enhancements seen in high-energy electron fluxes. However, there is an enhancement in the perpendicular electron fluxes at 90° pitch angle inside the magnetic hole, implying that the electrons are trapped within it. The variations of the electron velocity components V em and V en suggest that an electron vortex is formed by trapping electrons inside the magnetic hole in the cross-section in the M–N plane. These observations demonstrate the existence of a new type of coherent structures behaving as an electron vortex magnetic hole in turbulent space plasmas as predicted by recent kinetic simulations.

Huang, SY

Sahraoui, F

Yuan, ZG

He, JS

Zhao, JS

Le Contel, O

Deng, XH

Zhou, M

Fu, HS

Shi, QQ

Lavraud, B

Pang, Y

Yang, J

Wang, DD

Li, HM

Yu, XD

Pollock, CJ

Giles, BL

Torbert, RB

Russell, CT

Goodrich, KA

Gershman, DJ

Moore, TE

Ergun, RE

Khotyaintsev, YV

Lindqvist, P-A

Strangeway, RJ

Magnes, W

Bromund, K

Leinweber, H

Plaschke, F

Anderson, BJ

Burch, JL

published 

February 20, 2017

Astronomy & Astrophysics

Letters of the Astrophysical Journal  Journal