Propagation of Ultra High Energy Cosmic Rays in Cosmic Magnetic Fields

The origin of Ultra High Energy Cosmic Rays (UHECRs) constitutes an open question in Astrophysics, since the presence of Extragalactic Magnetic Fields (EGMFs), that permeate our Universe, can interfere with their propagation by deflecting their trajectories, leading them into a diffusive regime of propagation. This effect, the so-called magnetic horizon, limits the distance that those particles can travel and impacts on the observed spectrum of UHECRs by reducing the detected flux. Hence, the aim of this Thesis is to quantify the influence of the magnetic horizon studying the propagation of a population of ultra high energy cosmic protons. This is done by the Julia-based code UMAREL, specifically designed for this research, which injects protons in a simulated portion of the Universe recreated by the ENZO cosmological simulation which exploits the latest LOFAR observations of the Residual Rotation Measure (RRM). In this way, UMAREL has at its disposal realistic values for the magnetic field strengths and, taking into account the energy loss mechanisms that the protons experience, it can trace hypothetical and feasible trajectories of UHECRs in moving through cosmic magnetic fields. In such manner, it is possible to concretely observe the impact of the magnetic fields on the motion of the particles and to test which propagation regime, among the ones proposed by literature, best reproduces our measurements.