The escape model for Galactic cosmic rays

24th European Cosmic Ray Symposium

Giacinti, G.^1 ; Kachelrieß, M.^2 ; Semikoz, D.V.^3

University of Oxford, Clarendon Laboratory, Oxford, United Kingdom^1

Institutt for Fysikk, NTNU, Trondheim, Norway^2

AstroParticle and Cosmology (APC), Paris, France^3

关键词: Coherence lengths;    Dipole anisotropy;    Galactic cosmic rays;    Galactic magnetic fields;    Injection spectra;    Intermediate energy region;    Starburst galaxies;    Turbulent magnetic fields;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/632/1/012094/pdf
DOI  :  10.1088/1742-6596/632/1/012094

来源: IOP

【 摘 要 】

The escape model explains the cosmic ray (CR) knee by energy-dependent CR leakage from the Milky Way, with an excellent fit to all existing data. We test this model calculating the trajectories of individual CRs in the Galactic magnetic field. We find that the CR escape time τesc(E) exhibits a knee-like structure around E/Z = few × 1015eV for small coherence lengths and strengths of the turbulent magnetic field. The resulting intensities for different groups of nuclei are consistent with the ones determined by KASCADE and KASCADE-Grande, using simple power-laws as injection spectra. The transition from Galactic to extragalactic CRs happens in this model at low energies and is terminated below ≈ 3 × 1018eV. The intermediate energy region up to the ankle is populated by CRs accelerated in starburst galaxies. This model provides a good fit to ln(A) data, while the estimated CR dipole anisotropy is close to, or below, upper limits in the energy range 1017- 1018eV. The phase of the dipole is expected to change between 1 × 1017and 3 × 1018eV.