A common solution to the cosmic ray anisotropy and gradient problems

TL;DR

This paper proposes a propagation model linking cosmic ray escape time with magnetic turbulence, successfully explaining observed CR spectra, anisotropy, and gamma-ray distribution.

Contribution

It introduces a physically motivated correlation between CR escape time and magnetic turbulence, resolving multiple longstanding issues in cosmic ray propagation models.

Findings

Fits a wide set of CR primary and secondary spectra

Reproduces CR anisotropy in 10^2 - 10^4 GeV range

Matches gamma-ray longitude distribution from Fermi-LAT

Abstract

Multichannel Cosmic Ray (CR) spectra and the large scale CR anisotropy can hardly be made compatible in the framework of conventional isotropic and homogeneous propagation models. These models also have problems explaining the longitude distribution and the radial emissivity gradient of the $\gamma$-ray galactic interstellar emission. We argue here that accounting for a well physically motivated correlation between the CR escape time and the spatially dependent magnetic turbulence power can naturally solve both problems. Indeed, by exploiting this correlation we find propagation models that fit a wide set of CR primary and secondary spectra, and consistently reproduce the CR anisotropy in the energy range $10^2 - 10^4 \GeV$ and the $\gamma$-ray longitude distribution recently measured by Fermi-LAT.