A common solution to the cosmic ray anisotropy and gamma-ray gradient problems

Abstract

International audienceMultichannel Cosmic Ray (CR) spectra and the large scale CR anisotropy canhardly be made compatible in the framework of conventional isotropic andhomogeneous propagation models. These models also have problems explaining thelongitude distribution and the radial emissivity gradient of the $\gamma$-raygalactic interstellar emission. We argue here that accounting for a wellphysically motivated correlation between the CR escape time and the spatiallydependent magnetic turbulence power can naturally solve both problems. Indeed,by exploiting this correlation we find propagation models that fit a wide setof CR primary and secondary spectra, and consistently reproduce the CRanisotropy in the energy range 10^2 - 10^4 \GeV and the $\gamma$-raylongitude distribution recently measured by Fermi-LAT