Switchbacks Boundaries Observed by Parker Solar Probe: Statistical Analysis to Reveal their Dynamical Evolution in the Solar Wind

Magnetic switchbacks are sudden large deflections of the magnetic field, and are commonly observed by Parker Solar Probe (PSP) in the solar wind. Their nature and origin are still unestablished. We aim to present a more in-depth description of all magnetic deflections, including the largest ones that are called switchbacks, conducting a statistical analysis over the first twelve solar encounters of PSP.

We identify these deflections using measurements from the MAG fluxgate magnetometer, which is part of the FIELDS instrument suite. The detection is based on the deflection of the magnetic field from the Parker spiral. The electron pitch-angle flux measured by SWEAP/SPAN-E allows us to check the relative orientation of the strahl within the magnetic structures and then validate their identification.

In this study we concentrate on the boundary of these structures and investigate their properties (thickness, type of discontinuity, etc.) versus their distance from the Sun. Of particular interest is their dependence on the magnitude of the deflection. Our results reveal a prevalence of tangential discontinuities, which is linked to the alfvenic nature of these deflections. This has major implications on their dynamical evolution as they propagate away from the Sun.