Common solution to the cosmic ray anisotropy and gradient problems

Phys Rev Lett. 2012 May 25;108(21):211102. doi: 10.1103/PhysRevLett.108.211102. Epub 2012 May 23.

Abstract

Multichannel cosmic ray spectra and the large scale cosmic ray 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 γ-ray Galactic interstellar emission. We argue here that accounting for a physically motivated correlation between the cosmic ray 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 cosmic ray spectra, and consistently reproduce the cosmic ray anisotropy in the energy range 10(2)-10(4) GeV and the γ-ray longitude distribution recently measured by Fermi-LAT.