The Extension and Shape of the Collecting Zones of the Galactic Cosmic Rays from Helium to Iron

Hundreds of millions of cosmic-ray trajectories, from helium to iron, have been simulated in the Galactic disk in order to calculate the mean distance of cosmic-ray sources from Earth. The dominant parameter affecting the distance is the Galactic magnetic field, which makes cosmic-ray trajectories about 3 orders of magnitudes longer than the physical distance from the source to Earth. The calculations indicate that cosmic-ray sources powering the local flux around Earth are mainly disseminated along the regular magnetic field lines of the Galaxy. The spatial distribution of the sources form characteristic figures in the disk volume, which we define as the collecting regions of cosmic rays. Assuming cosmic-ray sources to be uniformly distributed in the disk of the Milky Way, at the arbitrary energy of 1 TeV amu-1 the typical length and width of these regions are 29.9 and 0.53 kpc for helium and 20.0 and 0.27 kpc for iron. The mean physical distance of the cosmic-ray sources from Earth turns out to be 3.5 kpc for helium and 1.6 kpc for iron.