Suprathermal electron characteristics observed by the Parker Solar Probe

The solar wind electron typically comprises core, halo, and strahl electrons. In this study, we focused on the suprathermal (halo and strahl) electron characteristics observed by the Parker Solar Probe (PSP). In the first study, we investigate localized deviations from the nominal Parker spiral magnetic field in the solar wind called switchbacks. 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. The sunward deficit in the electron velocity distribution function (eVDF) typically observed near the Sun is filled in at larger rotation angles. This results in the suprathermal electron density and heat flux in the anti-strahl 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, which 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 anti-strahl 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 PSP observations therefore support an enhanced role for wave-particle interactions in switchbacks. Two possible wave-particle interactions that could alter the eVDF inside switchbacks are whistler waves and kinetic Alfve ́n waves (KAW).