The Signatures of Electron Landau Damping in the Solar Wind

Using gyrokinetic simulations of solar wind turbulence and the field-particle correlation technique, we characterize signatures of particle energization via electron Landau damping in solar wind conditions. The field-particle correlation technique uses electromagnetic field and particle distribution measurements from a single spatial point to reveal mechanism-specific signatures of net changes in phase space energy density. Therefore, it is applicable to space-based missions and can increase the scientific return of in situ data. Electron Landau damping is thought to play a key role in the dissipation of turbulent energy in the solar wind, which motivates our goal of developing a framework with which to identify and interpret these signatures in observational data. To this end, we run four 3D-2V gyrokinetic turbulence simulations at varying plasma beta relevant to the inner heliosphere. Within this synthetic data we find signatures of electron Landau damping of dispersive kinetic Alfvén waves and characterize how they change with distance from the Sun, using beta as a proxy. Additionally, since the sampling cadence of a spacecraft can be lower than the frequency of a plasma wave undergoing collisionless damping at electron scales, we develop a rule of thumb for the field-particle correlation technique's ability to uncover these signatures even from undersampled data.