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Constraining models for the origin of ultra-high-energy cosmic rays with a novel combined analysis of arrival directions, spectrum, and composition data measured at the Pierre Auger Observatory
- Source :
- JCAP01(2024)022
- Publication Year :
- 2023
-
Abstract
- The combined fit of the measured energy spectrum and shower maximum depth distributions of ultra-high-energy cosmic rays is known to constrain the parameters of astrophysical models with homogeneous source distributions. Studies of the distribution of the cosmic-ray arrival directions show a better agreement with models in which a fraction of the flux is non-isotropic and associated with the nearby radio galaxy Centaurus A or with catalogs such as that of starburst galaxies. Here, we present a novel combination of both analyses by a simultaneous fit of arrival directions, energy spectrum, and composition data measured at the Pierre Auger Observatory. We find that a model containing a flux contribution from the starburst galaxy catalog of around 20% at 40 EeV with a magnetic field blurring of around $20^\circ$ for a rigidity of 10 EV provides a fair simultaneous description of all three observables. The starburst galaxy model is favored with a significance of $4.5\sigma$ (considering experimental systematic effects) compared to a reference model with only homogeneously distributed background sources. By investigating a scenario with Centaurus A as a single source in combination with the homogeneous background, we confirm that this region of the sky provides the dominant contribution to the observed anisotropy signal. Models containing a catalog of jetted active galactic nuclei whose flux scales with the $\gamma$-ray emission are, however, disfavored as they cannot adequately describe the measured arrival directions.
- Subjects :
- Astrophysics - High Energy Astrophysical Phenomena
Subjects
Details
- Database :
- arXiv
- Journal :
- JCAP01(2024)022
- Publication Type :
- Report
- Accession number :
- edsarx.2305.16693
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1088/1475-7516/2024/01/022