Indications of Negative Evolution for the Sources of the Highest Energy Cosmic Rays

Abstract

Using recent measurements of the spectrum and chemical composition of the highest energy cosmic rays, we consider the sources of these particles. We find that the data strongly prefers models in which the sources of the ultra-high energy cosmic rays inject predominantly intermediate mass nuclei, with comparatively few protons or heavy nuclei, such as iron or silicon. If the number density of sources per comoving volume does not evolve with redshift, the injected spectrum must be very hard ($\alpha \simeq 1$) in order to fit the spectrum observed at Earth. Such a hard spectral index would be surprising and difficult to accommodate theoretically. In contrast, much softer spectral indices, consistent with the predictions of Fermi acceleration ($\alpha \simeq 2$), are favored in models with negative source evolution. With this theoretical bias, these observations thus favor models in which the sources of the highest energy cosmic rays are preferentially located within the low-redshift universe.

9 pages, 4 figures

References in corpus (15)

• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Depth of Maximum of Air-Shower Profiles at the Pierre Auger Observatory: Measurements at Energies above 10^17.8 eV
• Cosmogenic Neutrinos: parameter space and detectabilty from PeV to ZeV
• Analytical solutions for energy spectra of electrons accelerated by nonrelativistic shock-waves in shell type supernova remnants
• GZK Neutrinos after the Fermi-LAT Diffuse Photon Flux Measurement
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• Observational Constraints on the Ultra-high Energy Cosmic Neutrino Flux from the Second Flight of the ANITA Experiment
• Star-forming galaxies as the origin of diffuse high-energy backgrounds: Gamma-ray and neutrino connections, and implications for starburst history
• On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
• A Galactic Halo Origin of the Neutrinos Detected by IceCube
• A complete model of the CR spectrum and composition across the Galactic to Extragalactic transition
• Search for Point-Like Sources of Ultra-High Energy Neutrinos at the Pierre Auger Observatory and Improved Limit on the Diffuse Flux of Tau Neutrinos
• High-energy gamma-ray and neutrino backgrounds from clusters of galaxies and radio constraints
• Ultrahigh Energy Neutrinos at the Pierre Auger Observatory
• A search for point sources of EeV photons

Cited by in corpus (60)

• Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory
• The Giant Radio Array for Neutrino Detection (GRAND): Science and Design
• Open Questions in Cosmic-Ray Research at Ultrahigh Energies
• 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
• Origin of the ankle in the ultra-high energy cosmic ray spectrum and of the extragalactic protons below it
• Cosmogenic photon and neutrino fluxes in the Auger era
• A new view on Auger data and cosmogenic neutrinos in light of different nuclear disintegration and air-shower models
• Low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei
• Determining the fraction of cosmic-ray protons at ultra-high energies with cosmogenic neutrinos
• Progress in unveiling extreme particle acceleration in persistent astrophysical jets
• Tidally disrupted stars as a possible origin of both cosmic rays and neutrinos at the highest energies
• Cosmogenic Neutrinos Challenge the Cosmic Ray Proton Dip Model
• Effects of uncertainties in simulations of extragalactic UHECR propagation, using CRPropa and SimProp
• Ultrahigh-energy Cosmic-ray Nuclei from Black Hole Jets: Recycling Galactic Cosmic Rays through Shear Acceleration
• Connecting blazars with ultra high energy cosmic rays and astrophysical neutrinos
• Robust Constraints and Novel Gamma-Ray Signatures of Dark Matter That Interacts Strongly With Nucleons
• 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
• Deciphering Contributions to the Extragalactic Gamma-Ray Background from 2 GeV to 2 TeV
• A Case for Radio Galaxies as the Sources of IceCube's Astrophysical Neutrino Flux
• Active Galactic Nuclei and the Origin of IceCube's Diffuse Neutrino Flux
• Nuclear Physics Meets the Sources of the Ultra-High Energy Cosmic Rays
• Radio Galaxies Dominate the High-Energy Diffuse Gamma-Ray Background
• Unified model for cosmic rays above $10^{17}$ eV and the diffuse gamma-ray and neutrino backgrounds
• Bayesian constraints on the astrophysical neutrino source population from IceCube data
• Bayesian Inference Constraints on Astrophysical Production of Ultra-high Energy Cosmic Rays and Cosmogenic Neutrino Flux Predictions
• Indication of a Local "Fog" of Sub-Ankle UHECR
• Superheavy Dark Matter and ANITA's Anomalous Events
• Scrutinizing FR 0 Radio Galaxies as Ultra-High-Energy Cosmic Ray Source Candidates
• Acceleration and propagation of ultra high energy cosmic rays
• Extragalactic magnetic field constraints from ultra-high-energy cosmic rays from local galaxies
• Modeling the spectrum and composition of ultrahigh-energy cosmic rays with two populations of extragalactic sources
• Diffuse flux of ultra-high energy photons from cosmic-ray interactions in the disk of the Galaxy and implications for the search for decaying super-heavy dark matter
• Energetics of ultrahigh-energy cosmic-ray nuclei
• Prospects for ultra-high-energy particle acceleration at relativistic shocks
• Ultrahigh energy cosmic rays and neutrinos from light nuclei composition
• PeV-EeV neutrinos from gamma-ray blazars due to ultrahigh-energy cosmic-ray propagation
• High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies
• On the Measurement of the Helicity of Intergalactic Magnetic Fields Using Ultra-High-Energy Cosmic Rays
• Constraints on Neutrino Emission from Nearby Galaxies Using the 2MASS Redshift Survey and IceCube
• UHECR Echoes from the Council of Giants
• Ultrahigh-energy neutrinos as a probe of espresso-shear acceleration in jets of Centaurus A
• The spectra and composition of Ultra High Energy Cosmic Rays and the measurement of the proton-air cross section
• High-Energy Neutrino Emission from Espresso-Reaccelerated Ions in Jets of Active Galactic Nuclei
• Can we reconcile the TA excess and hotspot with Auger observations?
• Impact of the finite life-time of UHECR sources
• Surprises from extragalactic propagation of UHECRs
• Future prospects of testing Lorentz invariance with UHECRs
• The role of supernovae inside AGN jets in UHECR acceleration
• Evidence for UHECR origin in starburst galaxies
• Effects of large-scale magnetic fields on the observed composition of ultra high-energy cosmic rays
• Combined Fit of Spectrum and Composition for FR0 Radio-galaxy-emitted Ultra-high-energy Cosmic Rays with Resulting Secondary Photons and Neutrinos
• The H.E.S.S. extragalactic sky survey with the first decade of observations
• Implication of the non-detection of neutrinos above 2PeV
• Modeling Hadronic Interactions in Ultra-High-Energy Cosmic Rays within Astrophysical Environments: A Parametric Approach
• The Contribution From TeV Halos to the Isotropic Gamma-Ray Background
• Extragalactic Searches for Dark Matter Annihilation
• Astrophysical interpretation of Pierre Auger Observatory measurements of the UHECR energy spectrum and mass composition
• Ultra high-energy cosmic rays from beyond the Greisen-Zatsepin-Kuz'min horizon
• Ultrahigh energy cosmic ray nuclei from remnants of dead quasars