Ultra-high energy cosmic rays: origin and propagation

• Autor(a) principal: Armand, Johnnier Pérez
• Data de Publicação: 2023
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/43/43134/tde-15052023-181859/
• topic: astrofsica; astrophysics; chuveiros atmosféricos extensos, Observatório Pierre Auger; cosmic rays; cosmologia; cosmology; extensive air showers; Pierre Auger obser- vatory; raios cósmicos

Cosmic rays are highly energetic charged nuclei that propagate through intergalactic space being the most energetic particles ever detected on Earth. Even though they have been exhaustively studied since their discovery more than 100 years ago, there are still many open questions in the field regarding the sources and mechanisms of creation and acceleration, chemical composition, energy spectrum, and arrival directions distribution, among others, which are the goal of current research. The main objective of this work is to explore astrophysical scenarios of origin and propagation consistent with the energy spectrum and depth of shower maximum (Xmax ) data collected by the Pierre Auger Observatory in the region of ultra-high energies (E > 10^17.5 eV) over a period of more than 15 years of observations. The astrophysical models were constructed using the Monte Carlo code CRPropa to simulate the cosmic ray extragalactic propagation. Special attention is given to the processes involving energy losses resulting from the particles interaction with the cosmic radiation fields as well as to the influence of the cosmic magnetic fields over the particles trajectories in their journey from the points of injection at the sources to the detection at Earth. We quantified the role of Xmax in breaking degeneracies in the parameter space of the astrophysical models used. We also extended previous analyses in the literature combining cosmic-ray energy spectrum and Xmax data, performed in the absence of magnetic fields, to the case where extragalactic magnetic deflections are present.