Magnetohydrodynamic turbulence and propagation of cosmic rays: theory confronted with observations

TL;DR

This paper reviews recent advances in understanding how magnetohydrodynamic turbulence influences cosmic ray propagation, integrating theoretical developments with observational data to challenge traditional homogeneous transport models.

Contribution

It introduces a new perspective by connecting MHD turbulence properties with cosmic ray transport, considering the ISM's multiphase nature and observational constraints.

Findings

Turbulence properties vary spatially in the ISM.

Observations challenge the assumption of homogeneous cosmic ray transport.

Different regimes of particle transport are identified and analyzed.

Abstract

Cosmic ray propagation is determined by the properties of interstellar turbulence. The multiphase nature of interstellar medium (ISM) and diversity of driving mechanisms give rise to spatial variation of turbulence properties. Meanwhile, precision astroparticle experiments pose challenges to the conventional picture of homogeneous and isotropic transport of cosmic rays (CRs). We are opening a new horizon for CR propagation research when studies of particle transport and interstellar turbulence confront each other. Here we review our recent developement on understandings of magnetohydrodynamic (MHD) turbulence and its connection to the fundamental processes governing cosmic ray propagation, different regimes of particle transport, that are augmented with observational discovery and analysis from multi-wavelength observations.