Nonthermal Particle Acceleration in Magnetized Turbulence

We discuss how turbulence efficiently accelerates particles in highly magnetized (low-β) plasmas. We will show that magnetized turbulence accelerates ions and electrons into nonthermal energy distributions with power-law ranges. We find that the ion spectrum is harder than the electron spectrum, and both distributions become harder for lower β values. We also find that the energization of electrons is accompanied by a significant energy-dependent pitch-angle anisotropy, with most electrons moving parallel to the local magnetic field, while ions remain roughly isotropic. We will show that particle injection from the thermal pool occurs in regions of high current density associated with magnetic reconnection, while scattering off larger scale turbulence fluctuations drives acceleration to higher energies. We will discuss the implications of these findings for understanding the origin of nonthermal particles in space and astrophysical plasmas.