Relaxation and Coherent Structures in Space Plasma Turbulence

In space plasmas, turbulent relaxation processes lead to the spontaneous formation of long-lived, coherent structures. By combining solar wind observations, theoretical models, and numerical simulations, we demonstrate how the plasma locally evolves toward metastable, force-free equilibria. These persistent vortices, observed within the turbulent inertial range, act as sites for particle energization and trapping, directly influencing transport and acceleration — especially in reconnection regions between interacting magnetic islands. Recent high-resolution Magnetospheric Multiscale (MMS) measurements in the magnetosheath provide direct observational evidence of such structures, confirming their central role in mediating the turbulent cascade and dissipation. This study was carried out within the Space It Up project, funded by the Italian Space Agency (ASI) and the Ministry of University and Research (MUR), under Contract Grant Nos. 2024-5-E.0-CUP and I53D24000060005.