Journal of Experimental and Theoretical Physics. Vol. 136, No. 6, Pages 704-710, 2023

K. Dolgikh^a^,^b^,*, A. Korochkin^b^,^c, G. Rubtsov^a^,^b, D. Semikoz^d, and I. Tkachev^a^,^b

^aInstitute for Nuclear Research of the Russian Academy of Sciences, Moscow, 117312 Russia

^bPhysics Department and Laboratory of Cosmology and Elementary Particle Physics, Novosibirsk State University, Novosibirsk, 630090 Russia

^cUniversité Libre de Bruxelles, CP225 Boulevard du Triomphe, Brussels, 1050 Belgium

^dAPC, Université Paris Cité, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Paris, 119 75205 France

Abstract—UHECR propagation in a turbulent intergalactic magnetic field in the small-angle scattering regime is well understood for propagation distances much larger than the field coherence scale. The diffusion theory doesn’t work and unexpected effects may appear for propagation over smaller distances, from a few and up to 10–20 coherence scales. We study the propagation of UHECRs in this regime, which may be relevant for intermediate mass UHECR nuclei and nG scale intergalactic magnetic fields with 1 Mpc coherence scale. We found that the trajectories form a non-trivial caustic-like pattern with strong deviation from isotropy. Thus, measurements of the flux from a source at a given distance will depend on the position of the observer.

Caustic-Like Structures in UHECR Flux after Propagation in Turbulent Intergalactic Magnetic Fields