2017/10/31 by Stefan Hackstein, Franco Vazza, F. Vazza +4 · 82 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #COSMIC cancer database #Cosmic ray #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Magnetic field #Physics #Ultra-high-energy cosmic ray #Universe #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stx3354
published in Monthly Notices of the Royal Astronomical Society 475(2), 2519-2529 (Oxford University Press) · 12 pages, 9 figures
openalex publication_date 2017/12/29 · arxiv created 2018/01/05 · arxiv updated 2018/01/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We simulate the propagation of cosmic rays at ultra-high energies, ≳1018 eV, in models of extragalactic magnetic fields in constrained simulations of the local Universe. We use constrained initial conditions with the cosmological magnetohydrodynamics code enzo. The resulting models of the distribution of magnetic fields in the local Universe are used in the CRPropa code to simulate the propagation of ultra-high energy cosmic rays. We investigate the impact of six different magneto-genesis scenarios, both primordial and astrophysical, on the propagation of cosmic rays over cosmological distances. Moreover, we study the influence of different source distributions around the Milky Way. Our study shows that different scenarios of magneto-genesis do not have a large impact on the anisotropy measurements of ultra-high energy cosmic rays. However, at high energies above the Greisen–Zatsepin–Kuzmin (GZK)-limit, there is anisotropy caused by the distribution of nearby sources, independent of the magnetic field model. This provides a chance to identify cosmic ray sources with future full-sky measurements and high number statistics at the highest energies. Finally, we compare our results to the dipole signal measured by the Pierre Auger Observatory. All our source models and magnetic field models could reproduce the observed dipole amplitude with a pure iron injection composition. Our results indicate that the dipole is observed due to clustering of secondary nuclei in direction of nearby sources of heavy nuclei. A light injection composition is disfavoured, since the increase in dipole angular power from 4 to 8 EeV is too slow compared to observation by the Pierre Auger Observatory.