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

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.

References in corpus (16)

• Observation of a Large-scale Anisotropy in the Arrival Directions of Cosmic Rays above $8\times 10^{18}$ eV
• Radio observational constraints on Galactic 3D-emission models
• Measurement of the cosmic-ray energy spectrum above $2.5\times 10^{18}$ eV using the Pierre Auger Observatory
• Arrival Directions of Cosmic Rays above 32 EeV from Phase One of the Pierre Auger Observatory
• Simulations of ultra-high Energy Cosmic Rays in the local Universe and the origin of Cosmic Magnetic Fields
• Enhanced Cosmological GRB Rates and Implications for Cosmogenic Neutrinos
• Constraining the sources of ultra-high-energy cosmic rays across and above the ankle with the spectrum and composition data measured at the Pierre Auger Observatory
• Progress in high-energy cosmic ray physics
• Ultrahigh energy cosmic rays from a nearby extragalactic source in the diffusive regime
• Galactic and Extragalactic Magnetic Fields
• Diffusion of cosmic rays at EeV energies in inhomogeneous extragalactic magnetic fields
• What can be learnt from UHECR anisotropies observations? Paper I : large-scale anisotropies and composition features
• The Nuclear Window to the Extragalactic Universe
• UHECR arrival directions in the latest data from the original Auger and TA surface detectors and nearby galaxies
• Testing hadronic and photo-hadronic interactions as responsible for UHECR and neutrino fluxes from Starburst Galaxies
• Testing Model Predictions of Depth of Air-Shower Maximum and Signals in Surface Detectors using Hybrid Data of the Pierre Auger Observatory

Cited by in corpus (19)

• Search for Extremely-High-Energy Neutrinos and First Constraints on the Ultrahigh-Energy Cosmic-Ray Proton Fraction with IceCube
• Constraints on UHECR sources and extragalactic magnetic fields from directional anisotropies
• Impact of the Magnetic Horizon on the Interpretation of the Pierre Auger Observatory Spectrum and Composition Data
• Probing the Dark Dimension with Auger data
• Ultrahigh-energy neutrinos as a probe of espresso-shear acceleration in jets of Centaurus A
• The large-scale anisotropy and flux (de-)magnification of ultra-high-energy cosmic rays in the Galactic magnetic field
• Case for Centaurus A as the main source of ultrahigh-energy cosmic rays
• Prospects for gamma-ray emission from magnetar regions in CTAO observations
• Ultra-high-energy Cosmic Ray Sources can be Gamma-ray Dim
• New physics as a possible explanation for the Amaterasu particle
• Combined Fit of Spectrum and Composition for FR0 Radio-galaxy-emitted Ultra-high-energy Cosmic Rays with Resulting Secondary Photons and Neutrinos
• Observational strategies for ultrahigh-energy neutrinos: the importance of deep sensitivity for detection and astronomy
• What exactly did the Transformer learn from our physics data?
• UHECRs Propagation and their Multimessengers: Upper limits and the Impact of the Extragalactic Magnetic Field
• On gamma rays as predictors of UHECR flux in AGNs
• Energy evolution of cosmic-ray mass and intensity measured by the Pierre Auger Observatory
• Beyond the Local Void: A data-driven search for the origins of the Amaterasu particle
• A two-step strategy to identify episodic sources of gravitational waves and high energy neutrinos in starburst galaxies
• Impact of the EPOS.LHC-R hadronic interaction model on the Centaurus A ultrahigh-energy cosmic-ray scenario