Revisiting the distance to the nearest UHECR source: Effects of extra-galactic magnetic fields

TL;DR

This paper refines constraints on the nearest ultra-high-energy cosmic ray (UHECR) sources, emphasizing the influence of extragalactic magnetic fields and introducing a new semi-analytical propagation method.

Contribution

It presents a novel semi-analytical approach for UHECR propagation in turbulent magnetic fields and updates source distance constraints considering magnetic effects.

Findings

Local UHECR sources are within 25-100 Mpc depending on composition.

Magnetic fields create a low-energy horizon affecting cosmic ray propagation.

Constraints on source distance are robust despite magnetic field complexities.

Abstract

We update the constraints on the location of the nearest UHECR source. By analyzing recent data from the Pierre Auger Observatory using state-of-the-art CR propagation models, we reaffirm the need of local sources with a distance less than 25-100 Mpc, depending on mass composition. A new fast semi-analytical method for the propagation of UHECR in environments with turbulent magnetic fields is developed. The onset of an enhancement and a low-energy magnetic horizon of cosmic rays from sources located within a particular distance range is demonstrated. We investigate the distance to the nearest source, taking into account these magnetic field effects. The results obtained highlight the robustness of our constrained distances to the nearest source.