| Full text | |
| Author(s): |
de Oliveira, Caina
;
Lang, Rodrigo Guedes
;
Batista, Pedro
Total Authors: 3
|
| Document type: | Journal article |
| Source: | ASTROPHYSICAL JOURNAL; v. 981, n. 2, p. 11-pg., 2025-03-10. |
| Abstract | |
Active galactic nuclei (AGN) are among the main candidates for ultra-high-energy cosmic-ray (UHECR) sources. However, while some theoretical and phenomenological works favor AGNs as the main sources, recent works have shown that using the very-high-energy gamma-ray flux as a proxy for the UHECR flux leads to a bad agreement with data. In this context, the energy spectrum and composition data are hardly fitted. At the same time, the arrival directions map is badly described and a spurious dipole direction is produced. In this work, we propose a possible solution to these contradictions. Using the observed gamma-ray flux as a proxy may carry the implicit assumption of beamed UHECR emission and, consequently, its beam will remain collimated up to its detection on Earth. We show that assuming an isotropic UHECR emission and correcting the gamma-ray emission proxy by Doppler boosting can overcome the problem. The combined fit of the spectrum and composition is improved, with a change of reduced chi(2) from 4.6 to 3.1. In particular, the tension between the observed and modeled dipole directions can be reduced from 5.9 (2.1)sigma away from the data to 3.5 (1.1)sigma for E > 8 EeV (E > 32 EeV). We also show that this effect is particularly important when including AGNs of different classes in the same analysis, such as radio galaxies and blazars. (AU) | |
| FAPESP's process: | 19/10151-2 - Study of Ultra-High Energy Cosmic Rays with the Pierre Auger Observatory upgrade AugerPrime |
| Grantee: | Carola Dobrigkeit Chinellato |
| Support Opportunities: | Special Projects |
| FAPESP's process: | 22/01271-7 - Astroparticle physics in the era of CTA and SWGO |
| Grantee: | Luiz Vitor de Souza Filho |
| Support Opportunities: | Organization Grants - Scientific Meeting |
| FAPESP's process: | 21/01089-1 - Cherenkov Telescope Array: construction and first discoveries |
| Grantee: | Luiz Vitor de Souza Filho |
| Support Opportunities: | Special Projects |
| FAPESP's process: | 20/15453-4 - Production of high energetic astroparticles |
| Grantee: | Cainã de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |