# Extragalactic Sources and Propagation of UHECRs

## TL;DR

This paper discusses recent studies using the CRPropa 3 framework to simulate UHECR propagation, examining magnetic deflections, anisotropies, and source scenarios, with implications for UHECR astronomy and source identification.

## Contribution

It presents new insights into UHECR deflections, anisotropy origins, and source models using advanced simulations, highlighting the impact of magnetic fields and local sources.

## Key findings

- Protons with energies >60 EeV may experience small deflections allowing UHECR astronomy.
- Local source distribution influences large-scale anisotropy more than EGMF models.
- Difficulty reproducing low anisotropy levels suggests additional sources or stronger void magnetic fields.

## Abstract

With the publicly available astrophysical simulation framework for propagating extraterrestrial UHE particles, CRPropa 3, it is now possible to study realistic UHECR source scenarios including deflections in Galactic and extragalactic magnetic fields in an efficient way. Here we discuss three recent studies that have already been done in that direction. The first one investigates what can be expected in the case of maximum allowed intergalactic magnetic fields. Here is shown that, even if voids contain strong magnetic fields, deflections of protons with energies $\gtrsim 60 \; \text{EeV}$ from nearby sources might be small enough to allow for UHECR astronomy. The second study looks into several scenarios with a smaller magnetization focusing on large-scale anisotropies. Here is shown that the local source distribution can have a more significant effect on the large-scale anisotropy than the EGMF model. A significant dipole component could, for instance, be explained by a dominant source within 5 Mpc distance. The third study looks into whether UHECRs can come from local radio galaxies. If this is the case it is difficult to reproduce the observed low level of anisotropy. Therefore is concluded that the magnetic field strength in voids in the EGMF model used here is too low and/or there are additional sources of UHECRs that were not taken into account in these simulations.