Data-Driven Constraints on Cosmic-Ray Diffusion: Probing Self-Generated Turbulence in the Milky Way

TL;DR

This paper uses cosmic-ray data from multiple experiments to analyze the diffusion process in the Milky Way, finding support for models with smoothly varying diffusion coefficients linked to self-generated turbulence.

Contribution

It introduces a data-driven method to constrain cosmic-ray diffusion models, highlighting the compatibility with self-generated magnetic turbulence predictions.

Findings

Supports models with smooth diffusion coefficients

Current data do not favor inhomogeneous diffusion models

Suggests combining cosmic-ray and electromagnetic observations for future insights

Abstract

We employ a data-driven approach to investigate the rigidity and spatial dependence of the diffusion of cosmic rays in the turbulent magnetic field of the Milky Way. Our analysis combines data sets from the experiments Voyager, AMS-02, CALET, and DAMPE for a range of cosmic ray nuclei from protons to oxygen. Our findings favor models with a smooth behavior in the diffusion coefficient, indicating a good qualitative agreement with the predictions of self-generated magnetic turbulence models. Instead, the current cosmic-ray data do not exhibit a clear preference for or against inhomogeneous diffusion, which is also a prediction of these models. Future progress might be possible by combining cosmic-ray data with gamma rays or radio observations, enabling a more comprehensive exploration.