On the excess of ultra-high energy cosmic rays in the direction of Centaurus A

Abstract

A posteriori anisotropy study of ultra-high energy cosmic rays (UHECRs) with the Pierre Auger Observatory (PAO) has shown evidence of excess of cosmic ray particles above 55 EeV within $18^{\circ }$ of the direction of the radio galaxy Centaurus A. However, the origin of the excess remains elusive. We simulate the propagation of different species of particles coming from the direction of Centaurus A in the Galactic magnetic fields, and find that only particles of nuclear charge $Z\la 10$ can avoid being deflected outside of the $18^{\circ }$ window of Centaurus A. On the other hand, considering the increasingly heavy composition of UHECRs at the highest energies measured by PAO, a plausible scenario for cosmic rays from the direction of Centaurus A can be found if they consist of intermediate-mass nuclei. The chemical composition of cosmic rays can be further constrained by lower-energy cosmic rays of the same rigidity. We find that cosmic ray acceleration in the lobes of Centaurus A is not favored, while acceleration in the stellar winds that are rich in intermediate-mass nuclei, could meet the requirement. This suggests that the observed excess may originate from cosmic ray accelerators induced by stellar explosions in the star-forming regions of Centaurus A and/or the Centaurus cluster located behind Centaurus A.

arXiv comment9 pages, 6 figures, 1 table; ApJ accepted

References in corpus (50)

• COSMOLOGICAL GAMMA RAY BURSTS AND THE HIGHEST ENERGY COSMIC RAYS
• Correlation of the highest energy cosmic rays with nearby extragalactic objects
• Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
• On astrophysical solution to ultra high energy cosmic rays
• Measurement of the energy spectrum of cosmic rays above 10^18 eV using the Pierre Auger Observatory
• Pulsar rotation measures and the large-scale structure of Galactic magnetic field
• Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
• Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
• Measurement of the Flux of Ultrahigh Energy Cosmic Rays from Monocular Observations by the High Resolution Fly's Eye Experiment
• Indications of Proton-Dominated Cosmic Ray Composition above 1.6 EeV
• High Energy Neutrinos and Cosmic-Rays from Low-Luminosity Gamma-Ray Bursts?
• Light Curve and Spectral Models for the Hypernova SN 1998bw associated with GRB980425
• Pulsar rotation measures and the magnetic structure of our Galaxy
• The Distance to NGC 5128 (Centaurus A)
• High-energy cosmic-ray nuclei from high- and low-luminosity gamma-ray bursts and implications for multi-messenger astronomy
• Ultra high energy cosmic rays and the large scale structure of the galactic magnetic field
• Cosmic Ray Anisotropy Analysis with a Full-Sky Observatory
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• The spiral structure of our Milky Way Galaxy
• High-energy Particle Acceleration and Production of Ultra-high-energy Cosmic Rays in the Giant Lobes of Centaurus A
• Ultra High Energy Cosmic Rays from Black Hole Jets of Radio Galaxies
• High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae
• Tracing protons through the Galactic magnetic field: a clue for charge composition of ultra-high energy cosmic rays
• The Galactic magnetic field and propagation of ultra-high energy cosmic rays
• Stochastic particle acceleration in the lobes of giant radio galaxies
• On the Origin and Survival of UHE Cosmic-Ray Nuclei in GRBs and Hypernovae
• Cosmic rays from remnants of quasars?
• The need for a local source of UHE CR nuclei
• Ultra-High Energy Cosmic Ray production in the polar cap regions of black hole magnetospheres
• Triggered star-formation in the inner filament of Centaurus A
• Centaurus A as a source of extragalactic cosmic rays with arrival energies well beyond the GZK cutoff
• Hot gas flows on global and nuclear galactic scales
• The Pierre Auger Observatory II: Studies of Cosmic Ray Composition and Hadronic Interaction models
• Ultrahigh Energy Nuclei in the Turbulent Galactic Magnetic Field
• A population of weak metal-line absorbers surrounding the Milky Way
• Cen A as TeV gamma-ray and possible UHE cosmic-ray source
• The Jet-Heated X-ray Filament in the Centaurus A Northern Middle Radio Lobe
• Deflections of cosmic rays in a random component of the Galactic magnetic field
• On The Heavy Chemical Composition of the Ultra-High Energy Cosmic Rays
• An Auger test of the Cen A model of highest energy cosmic rays
• Ultra-High Energy Cosmic-Ray Acceleration in the Jet of Centaurus A
• The Centaurus A Ultrahigh-Energy Cosmic Ray Excess and the Local Extragalactic Magnetic Field
• Do Ultrahigh Energy Cosmic Rays Come from Active Galactic Nuclei and Fermi $\gamma$-ray Sources?
• Spectrum and Composition of Ultra-high Energy Cosmic Rays from Semi-relativistic Hypernovae
• Anisotropic AGN Outflows and Enrichment of the Intergalactic Medium. II. Metallicity
• Coherent and random UHECR Spectroscopy of Lightest Nuclei along CenA: Shadows on GZK Tau Neutrinos spread in a near sky and time
• Implications of the UHECRs penetration depth measurements
• Sensitivity of Extensive Air Showers to Features of Hadronic Interactions at Ultra-High Energies
• Physical conditions in nearby active galaxies correlated with ultra-high-energy cosmic rays detected by the Pierre Auger Observatory
• A New Limit on the Distances of Nuclei UHECRs Sources

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• A Case for Radio Galaxies as the Sources of IceCube's Astrophysical Neutrino Flux
• Constraints on the source of ultra-high energy cosmic rays using anisotropy vs chemical composition
• High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies
• Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model
• Probing UHECR production in Centaurus A using secondary neutrinos and gamma-rays
• Nearby active galactic nuclei and starburst galaxies as sources of the measured UHECRs anisotropy signal
• The origin of the very-high-energy radiation along the jet of Centaurus A