Single- and Multi-Particle Statistics of Magnetohydrodynamic Turbulence

Turbulence plays a fundamental role in many astrophysical flows such as convection in stars, stellar winds and the interstellar medium. Most astrophysical objects are composed of magnetised plasma. Astrophysical turbulence is thus characterised by the complex nonlinear interaction of flows with magnetic fields. Magnetohydrodynamic turbulence is known to differ significantly from standard hydrodynamic turbulence, especially in the presence of strong mean magnetic fields. The changes in the turbulence induced by the presence of magnetic fields can be observed in standard Eulerian diagnostics such as the energy spectra and the structure functions of the velocity field. They are even more clearly revealed in the Lagrangian statistics, which provide insight into the diffusive and dispersive flow dynamics and the relevant time scales in a turbulent flow. In this talk, statistical properties of homogeneous magnetohydrodynamic turbulence will be discussed with a focus on the Lagrangian perspective. New results will be presented for Lagrangian statistics based on both the motion of individual tracers as well as the relative motion of groups of particles