Speaker
Description
Turbulence and magnetic reconnection are intrinsic to space and astrophysical plasmas. Recent observations revealed a novel type of reconnection occurring in the turbulent Earth’s magnetosheath, dubbed “electron-only reconnection” [Phan 2018]. This distinctive form of reconnection occurs in the absence of ion outflows, signifying a reconnection event without an Ion Diffusion Region (IDR). 2D simulations have found that electron-only reconnection manifests when the current sheet's length is less than approximately 10 times the ion skin depth (d_i) [Califano et al. (2020)]. Moreover, for current sheets smaller than the ion gyroradius (ρ_i) the ion response is further weakened, further enhancing the reconnection rate [Guan 2023]. In this work, we perform 3D3V hybrid-Vlasov simulations of turbulence across and below the ion scales, exploring the occurrence of electron-only reconnection for different values of the ion beta (β_i = 0.25, 1, 4). Electron-inertia terms are included in the model, serving as a physical mechanism for collisionless magnetic reconnection to occur. In these simulations, electron only reconnection events are clearly identified. A spectral analysis of turbulent fluctuations is roughly consistent with a transition from Kinetic Alfvén Waves (KAW) to Inertial Kinetic Alfvén Wave (IKAW) and Whistler Wave regimes close to the scale of the electron skin depth. Velocity spectra show a clear decoupling between ions and electron as β_i increases, attributed to the presence of strong electron outflows in an Electron Dissipation Region (EDR) and the simultaneous absence of ion jets. Finally, turbulent heating of ions at different β_i is also addressed. The overall picture that emerges from this study has fundamental implications for the dynamics of space and astrophysical plasmas.
