Switchbacks in the Young Solar Wind: Electron Evolution Observed inside Switchbacks between 0.125 au and 0.25 au

Abstract

Switchbacks are localized deviations from the nominal Parker spiral field in the solar wind. In this study, we investigate the electron distributions inside switchbacks, focusing primarily on the suprathermal (halo and strahl) populations. We explore electron parameters in relation to the angle of rotation of the magnetic field from radial to determine whether electron distributions observed within switchbacks have any differences from those outside of switchbacks. Our observations reveal several trends in the suprathermal electron populations inside switchbacks. We find that the sunward deficit in the electron velocity distribution function typically observed near the Sun is filled in at larger rotation angles. This results in the suprathermal electron density and heat flux in the antistrahl direction changing from a negative to a positive value. On many days, we also observe a positive correlation between the halo density and rotation angle, and this may suggest that the growth of the halo may fill in the sunward deficit. We also find that strahl distributions have an increased average angular spread at large magnetic field rotation angles. The increase in suprathermal electron flux in the antistrahl direction, and the increase in strahl width, together could suggest that enhanced scattering occurs inside switchbacks. Electron core beta values tend to increase with the magnetic field rotation angle, mainly due to a decrease in magnetic pressure. An increase in electron beta may favor the growth of instabilities inside switchbacks. The Parker Solar Probe observations therefore support an enhanced role for wave–particle interactions in switchbacks.

The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations

“…This conclusion is also supported by the latest work of Nair et al (2022). F E is believed to be associated with the source regions of the footpoints of magnetic field lines, and its variations indicate the possible change of source regions or disconnection of magnetic field lines (Pagel et al 2005a(Pagel et al , 2005b.…”

“…The A E measures the anisotropic distributions of electrons at different pitch angles, which is associated with the pitch-angle scattering of electrons (Nair et al 2022), because the E-PADs are generally aligned well along the magnetic field lines (i.e., 0°F igure 1. Switchback event observed on 2021 January 18.…”