Shift of UHECR source images by the intergalactic magnetic field

We study the propagation of ultra-high-energy cosmic rays (UHECRs) in the local intergalactic magnetic field (IGMF) within a radius of <10 Mpc around the Milky Way. Assuming that the field strength is in the range of 1–3 nG and the correlation length is between 0.01 and 1 Mpc, we demonstrate that the IGMF can not only blur the source image but also shift its position, mimicking the effect of the coherent Galactic magnetic field (GMF). This introduces additional uncertainty in identifying UHECR sources due to the displacement of the source image in the IGMF. Unlike the image shift caused by the coherent GMF, which is determined by its global structure, the shift in the IGMF depends on the specific realization of the turbulent magnetic field between the source and the observer which is much more difficult to control. Finally, we apply this effect to potential sources of the UHECR excess in the Cen A region.