Cosmic Rays around $10^{18}$eV: Implications of Contemporary Measurements on the Origin of the Ankle Feature

Abstract

The impressive power-law decay of the energy spectrum of cosmic rays over more than thirty orders of magnitude in intensity and for energies ranging over eleven decades between $\simeq 10^9$eV and $\simeq 10^{20}$eV is actually dotted with small irregularities. These irregularities are highly valuable for uncovering and understanding the modes of production and propagation of cosmic rays. They manifest themselves through changes in the spectral index characterising the observed power laws. One of these irregularities, known as the \textit{ankle}, is subject to conflicting interpretations for many years. If contemporary observations characterising it have shed new lights, they are still far from being able to deliver all the story. The purpose of this contribution is to give an overview of the physics of cosmic rays in the energy range where the transition between Galactic and extragalactic cosmic rays is expected to occur, and to deliver several lines of thought about the origin of the ankle.

arXiv commentSolicited review paper to appear in "Comptes Rendus: Physique"

References in corpus (30)

• KASCADE measurements of energy spectra for elemental groups of cosmic rays: Results and open problems
• 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
• Indications of Proton-Dominated Cosmic Ray Composition above 1.6 EeV
• The Cosmic Ray Energy Spectrum Observed with the Surface Detector of the Telescope Array Experiment
• Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande
• Diffusive propagation of cosmic rays from supernova remnants in the Galaxy. II: anisotropy
• Spectrum of cosmic rays, produced in supernova remnants
• Ultra high energy cosmic rays: implications of Auger data for source spectra and chemical composition
• On the transition from Galactic to extragalactic cosmic-rays: spectral and composition features from two opposite scenarios
• Implications of the cosmic ray spectrum for the mass composition at the highest energies
• Ankle-like Feature in the Energy Spectrum of Light Elements of Cosmic Rays Observed with KASCADE-Grande
• The Tunka-133 EAS Cherenkov light array: status of 2011
• Extra-galactic magnetic fields and the second knee in the cosmic-ray spectrum
• Constraints on the origin of cosmic rays above $10^{18}$ eV from large scale anisotropy searches in data of the Pierre Auger Observatory
• Cosmic Ray Anisotropy as Signature for the Transition from Galactic to Extragalactic Cosmic Rays
• Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
• The primary cosmic ray composition between 10**15 and 10**16 eV from Extensive Air Showers electromagnetic and TeV muon data
• A Search for Point Sources of EeV Neutrons
• Extragalactic UHE proton spectrum and prediction for iron-nuclei flux at 10^8 - 10^9 GeV
• Cosmic ray spectrum and anisotropies from the knee to the second knee
• Large scale distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory
• On The Heavy Chemical Composition of the Ultra-High Energy Cosmic Rays
• On the shape of the UHE cosmic ray spectrum
• Origin of Ultrahigh Energy Galactic Cosmic Rays: The Isotropy Problem
• The isotropy problem of Sub-ankle Ultra-high energy cosmic rays
• Probing the Structure and Kinematics of the transition Layer between the Magellanic Stream and the Halo in HI
• The flux suppression at the highest energies
• Constraining UHECR source models by the TA SD energy spectrum

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
• Origin of the ankle in the ultra-high energy cosmic ray spectrum and of the extragalactic protons below it
• 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
• Ultrahigh-energy cosmic rays from tidally-ignited white dwarfs
• Diffusion of cosmic rays at EeV energies in inhomogeneous extragalactic magnetic fields
• Measurements and implications of cosmic ray anisotropies from TeV to trans-EeV energies
• On the Measurement of the Helicity of Intergalactic Magnetic Fields Using Ultra-High-Energy Cosmic Rays
• Large Scale Anisotropy of Cosmic Rays and Directional Neutrino Signals from Galactic Sources
• Are EeV cosmic rays isotropic at intermediate scales?
• Ultra-high energy cosmic rays with UFA-15 source model in Bumblebee gravity theory