Anisotropic particle acceleration in relativistic Alfvenic turbulence

Alfvénic turbulence is an effective mechanism for particle acceleration in strongly magnetized, relativistic plasma. We discuss scenarios where turbulent plasma is influenced by a strong guide magnetic field, resulting in highly anisotropic turbulent fluctuations [1,2]. In such cases, the magnetic moments of particles are conserved, and acceleration can only occur along the direction of the magnetic field. Consistent with previous analytic studies, we find through particle-in-cell simulations of magnetically dominated pair plasma that the momenta of accelerated particles are closely aligned with the magnetic field lines. Notably, the alignment angle decreases as particle energy increases, potentially limited only by the inherent curvature and gradients of the turbulent magnetic fluctuations. This finding has implications for interpreting the synchrotron radiation emitted by highly accelerated particles.

1. C. Vega, S. Boldyrev, V. Roytershteyn, Anisotropic particle acceleration in Alfvenic turbulence, ApJ, 985, 231, 2025;

2. C. Vega, S. Boldyrev, V. Roytershteyn, Particle Acceleration in Relativistic Alfvenic Turbulence, ApJ, 971, 106, 2024.