Reconstructing the Auger UHECR Dipole: A Hybrid Analysis of 4LAC AGNs and Nearby Starburst Galaxies

The large-scale dipole anisotropy observed by the Pierre Auger Observatory above $8$~EeV provides important clues about the origin of ultra-high-energy cosmic rays (UHECRs). In this work, we investigate whether gamma-ray active galactic nuclei (AGNs) from the Fermi-LAT Fourth AGN Catalog (4LAC) can explain the observed dipole and examine the contribution of nearby starburst galaxies (SBGs). Incorporating source fluxes, redshift distributions, GZK attenuation, and a mixed-composition framework, we demonstrate that single-source populations of AGNs and SBGs alone fail to reproduce the observed Auger dipole. To resolve this, we construct a hybrid AGN+SBG model. The best-fit solution for the $8$–$16$~EeV interval requires a $23$% AGN contribution and $45$% SBG contribution, which gives a dipole amplitude of $5.03$% while maintaining the dipole direction of (${104.1}^{\circ }$, $-{25.1}^{\circ }$) with angular separation of ${7.10}^{\circ }$. In the other energy intervals also, we find that the nearby SBGs increasingly dominate the anisotropic component while AGNs provide a subdominant contribution alongside a quasi-isotropic background.