Impact of the Galactic magnetic field modelling on studies of the UHECRs arrival direction

Ultra-high energy cosmic rays (UHECRs) are charged particles of extreme energy that experience
deflections in Galactic and extragalactic magnetic fields as they propagate to Earth. These
deflections limit the ability to trace their arrival directions back to their sources.
In this work, we investigate the impact of Galactic magnetic deflections on cross-correlation
analyses with source catalogs by modeling different configurations of the turbulent and coherent
fields. We show that even when magnetic deflections are applied to simulated data, the best-fit
parameters found by the Pierre Auger Collaboration for the correlation with starburst galaxies can
be recovered with high probability. However, a search for local overdensities in the simulations
predicts secondary structures that are absent in the data. By comparing data and simulations, we
demonstrate how these analyses can constrain the strength of the extragalactic magnetic field.