Origin of the light cosmic ray component below the ankle

Abstract

The origin and nature of the ultrahigh energy cosmic rays remains a mystery. However, considerable progress has been achieved in past years due to observations performed by the Pierre Auger Observatory and Telescope Array. Above $10^{18}$ eV the observed energy spectrum presents two features: a hardening of the slope at $\sim 10^{18.6}$ eV, which is known as the ankle, and a suppression at $\sim 10^{19.6}$ eV. The composition inferred from the experimental data, interpreted by using the current high energy hadronic interaction models, seems to be light below the ankle, showing a trend to heavier nuclei for increasing values of the primary energy. Also, the anisotropy information is consistent with an extragalactic origin of this light component that would dominate the spectrum below the ankle. Therefore, the models that explain the ankle as the transition from the galactic and extragalactic components are disfavored by present data. Recently, it has been proposed that this light component originates from the photodisintegration of more energetic and heavier nuclei in the source environment. The formation of the ankle can also be explained by this mechanism. In this work we study in detail this general scenario but in the context of the central region of active galaxies. In this case, the cosmic rays are accelerated near the supermassive black hole present in the central region of these types of galaxies, and the photodisintegration of heavy nuclei takes place in the radiation field that surrounds the supermassive black hole.

arXiv commentAccepted for publication in PRD

References in corpus (34)

• Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector
• EPOS LHC : test of collective hadronization with LHC data
• A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
• The Pierre Auger Cosmic Ray Observatory
• Monte Carlo treatment of hadronic interactions in enhanced Pomeron scheme: I. QGSJET-II model
• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Luminosity-dependent evolution of soft X-ray selected AGN: New Chandra and XMM-Newton surveys
• The Spectral Energy Distributions of Low-Luminosity Active Galactic Nuclei
• Monte-Carlo simulations of photohadronic processes in astrophysics
• Depth of Maximum of Air-Shower Profiles at the Pierre Auger Observatory: Measurements at Energies above 10^17.8 eV
• Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory
• Implications of Cosmological Gamma-Ray Absorption II. Modification of gamma-ray spectra
• CRPropa 3 - a Public Astrophysical Simulation Framework for Propagating Extraterrestrial Ultra-High Energy Particles
• The Cosmic Evolution of Fermi BL Lacertae Objects
• Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data
• Study of Ultra-High Energy Cosmic Ray Composition Using Telescope Array's Middle Drum Detector and Surface Array in Hybrid Mode
• Resolving the Extragalactic $\gamma$-ray Background above 50 GeV with Fermi-LAT
• Origin of the ankle in the ultra-high energy cosmic ray spectrum and of the extragalactic protons below it
• Ultra high energy cosmic rays: implications of Auger data for source spectra and chemical composition
• Implications of Particle Acceleration in Active Galactic Nuclei for Cosmic Rays and High Energy Neutrino Astronomy
• UHE nuclei propagation and the interpretation of the ankle in the cosmic-ray spectrum
• Ultra High Energy Cosmic Rays: The disappointing model
• UHECR acceleration at GRB internal shocks
• A complete model of the CR spectrum and composition across the Galactic to Extragalactic transition
• Anisotropies of ultra-high energy cosmic rays diffusing from extragalactic sources
• High energy radiation from Centaurus A
• Cosmogenic neutrinos and ultra-high energy cosmic ray models
• Large scale distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory
• A minimal model for extragalactic cosmic rays and neutrinos
• Cascade photons as test of protons in UHECR
• Underground Muon Counters as a Tool for Composition Analyses
• Very high energy neutrino emission from the core of low luminosity AGNs triggered by magnetic reconnection acceleration
• Implications of gamma-ray observations on proton models of UHECR
• Small-Angle Scattering and Diffusion: Application to Relativistic Shock Acceleration

Cited by in corpus (10)

• Features of the energy spectrum of cosmic rays above $2.5\times 10^{18}$ eV using the Pierre Auger Observatory
• Ultra-High-Energy Cosmic Rays
• 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 towards characterizing ultrahigh energy cosmic ray sources
• Testing hadronic and photo-hadronic interactions as responsible for UHECR and neutrino fluxes from Starburst Galaxies
• Modeling the spectrum and composition of ultrahigh-energy cosmic rays with two populations of extragalactic sources
• Impact of the Magnetic Horizon on the Interpretation of the Pierre Auger Observatory Spectrum and Composition Data
• Ultrahigh energy cosmic rays and neutrinos from light nuclei composition
• Determination of the Cosmic-Ray Chemical Composition: Open Issues and Prospects
• Modeling Hadronic Interactions in Ultra-High-Energy Cosmic Rays within Astrophysical Environments: A Parametric Approach