Bayesian analysis of the mass composition of Ultra-High Energy Cosmic Rays using Xmax data recorded at the Pierre Auger Observatory
- Torralba Elipe, Guillermo
- Enrique Zas Arregui Director
Universidade de defensa: Universidade de Santiago de Compostela
Fecha de defensa: 02 de novembro de 2017
- Andrew Watson Presidente/a
- Ricardo Vázquez López Secretario
- Lorenzo Cazón Boado Vogal
Tipo: Tese
Resumo
Understanding the composition of Ultra High Energy Cosmic Rays (UHECRs) at Earth is crucial to unveil their origin and propagation mechanisms, and it is thus one of the main current challenges in the field of Astroparticle Physics. This thesis is aimed to study the mass composition of UHECRs using data measured at the Pierre Auger Observatory in a Bayesian approach. An innovative method for composition analysis based on Bayesian statistics is developed. This is then applied to Auger data to infer the composition of UHECRs under different primary cosmic ray mass scenarios and assuming different hadronic interaction models. As a result a transition from intermediate to lighter masses from 0.63 EeV to 2 EeV is found. Above this energy the composition becomes heavier as energy increases. Using these results and the all particle spectrum measured at the Auger Observatory a first estimate of the proton flux is inferred and its astrophysical interpretations are discussed.