Particle acceleration by relativistic Alfvénic turbulence in a strong magnetic field*

Strong, magnetically dominated Alfvénic turbulence efficiently accelerates non-thermal particles in a relativistic collisionless plasma. We propose that when the magnetization is strong, the type of energy distribution achieved by accelerated particles depends on the relative strengths of turbulent fluctuations (δ B₀) and the guide field (B₀) [1]. If δB₀ is much smaller than B₀, the particles' magnetic moments are conserved, and the acceleration is caused by magnetic curvature drifts. Curvature acceleration energizes particles in the direction parallel to the magnetic field lines, resulting in log-normal tails of particle energy distribution functions. The accelerated particles have small pitch angles, which may impact the radiative signatures of astrophysical objects.

 

[1] Vega, C., Boldyrev, S., & Roytershteyn, V., arXiv:2405.07891 (2024).