# Propagation of UHECRs in the local Universe and origin of cosmic magnetic fields

## TL;DR

This study simulates ultra-high-energy cosmic ray propagation in the local Universe to understand how different magnetic field origins affect anisotropy and source distribution, aligning with observations from the Pierre Auger Observatory.

## Contribution

It demonstrates that magneto-genesis scenarios have limited impact on anisotropy, and that source distribution and composition explain observed cosmic ray anisotropy.

## Key findings

- Magneto-genesis scenarios do not significantly affect anisotropy measurements.
- Nearby source distribution causes anisotropy at very high energies.
- Pure iron injection models reproduce the observed dipole amplitude.

## Abstract

We simulate the propagation of cosmic rays at ultra-high energies, $\gtrsim 10^{18}$ eV, in models of extragalactic magnetic fields in constrained simulations of the local Universe. We investigate the impact of different magneto-genesis scenarios, both, primordial and astrophysical, on the propagation of cosmic rays. Our study shows that different scenarios of magneto-genesis do not have a large impact on the anisotropy measurements. The distribution of nearby sources causes anisotropy at very high energies, independent of the magnetic field model. We compare our results to the dipole signal measured by the Pierre Auger Observatory. All our models could reproduce the observed dipole amplitude with a pure iron injection composition. This is due to clustering of secondary nuclei in direction of nearby sources of heavy nuclei. A light injection composition is disfavoured by the non-observation of anisotropy at energies of 4 - 8 EeV.