Speaker
Dr
Gwenael Giacinti
(Oxford U.)
Description
We show that the cosmic ray (CR) knee can be entirely explained by energy-dependent CR
leakage from the Milky Way, with an excellent fit to all existing data. We test this hypothesis
calculating the trajectories of individual CRs in the Galactic magnetic field. We find that the CR
escape time t(E) exhibits a knee-like structure around E/Z = few × PeV 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, normalized to CREAM data. Thus the escape model describes successfully
the data of individual
groups of nuclei from E/Z = TeV up to 0.1 EeV energies. The transition from Galactic to extragalactic CRs
is terminated at ≈ 2 EeV, while extragalactic CRs contribute sizeable to the subdominant proton flux already
for > 20 PeV.The escape model provides a good fit to ln(A) data; it predicts that the phase of the
CR dipole varies strongly in the energy range between 0.1 EeV and 3 EeV, in agreement with
determinations of the phase by Auger. Our estimate for the dipole magnitude is consistent with observations.
| Registration number following "ICRC2015-I/" | 623 |
|---|---|
| Collaboration | -- not specified -- |
