A global autocorrelation study after the first Auger data: impact on the number density of UHECR sources

Abstract

We perform an autocorrelation study of the Auger data with the aim to constrain the number density n_s of ultrahigh energy cosmic ray (UHECR) sources, estimating at the same time the effect on $n_s$ of the systematic energy scale uncertainty and of the distribution of UHECR. The use of global analysis has the advantage that no biases are introduced, either in n_s or in the related error bar, by the a priori choice of a single angular scale. The case of continuous, uniformly distributed sources is nominally disfavored at 99% C.L. and the fit improves if the sources follow the large-scale structure of matter in the universe. The best fit values obtained for the number density of proton sources are within a factor ~2 around n_s ~ 10^{-4}/Mpc^3 and depend mainly on the Auger energy calibration scale, with lower densities being preferred if the current scale is correct. The data show no significant small-scale clustering on scales smaller than a few degrees. This might be interpreted as a signature of magnetic smearing of comparable size, comparable with the indication of a ~3 degrees magnetic deflection coming from cross-correlation results. The effects on the above results of some approximations done is also discussed.

9 pages, 4 figures, 2 tables; v2: added discussions on the role of the energy cut and the chemical composition; to appear in ApJ

References in corpus (41)

• Correlation of the highest energy cosmic rays with nearby extragalactic objects
• First Observation of the Greisen-Zatsepin-Kuzmin Suppression
• Observation of the suppression of the flux of cosmic rays above 4x10^19eV
• The PSCz Catalogue
• On astrophysical solution to ultra high energy cosmic rays
• Turbulence and Magnetic Fields in the Large Scale Structure of the Universe
• Small-scale anisotropy of cosmic rays above 10^19eV observed with the Akeno Giant Air Shower Array
• Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
• Nuclear Reaction Network for Primordial Nucleosynthesis: a detailed analysis of rates, uncertainties and light nuclei yields
• Upper limit on the cosmic-ray photon flux above 10^19 eV using the surface detector of the Pierre Auger Observatory
• Ultra-High Energy Cosmic Ray Probes of Large Scale Structure and Magnetic Fields
• Upper limit on the diffuse flux of UHE tau neutrinos from the Pierre Auger Observatory
• The Changing AGN Population
• Giant AGN Flares and Cosmic Ray Bursts
• High-energy Particle Acceleration and Production of Ultra-high-energy Cosmic Rays in the Giant Lobes of Centaurus A
• BL Lacertae are probable sources of the observed ultra-high energy cosmic rays
• Ultra-High Energy Cosmic Rays in a Structured and Magnetized Universe
• Mapping deflections of extragalactic Ultra-High Energy Cosmic Rays in magnetohydrodynamic simulations of the Local Universe
• On the Evidence for Clustering in the Arrival Directions of AGASA's Ultrahigh Energy Cosmic Rays
• The optical depth of the Universe to ultrahigh energy cosmic ray scattering in the magnetized large scale structure
• Searching for a Correlation Between Cosmic-Ray Sources Above 10^{19} eV and Large-Scale Structure
• The Galactic magnetic field as spectrograph for ultra-high energy cosmic rays
• High energy radiation from Centaurus A
• The Small Scale Anisotropies, the Spectrum and the Sources of Ultra High Energy Cosmic Rays
• Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
• Ultra-high energy Neutrinos from Centaurus A and the Auger hot spot
• Small Scale Clustering in the Isotropic Arrival Distribution of Ultra-High Energy Cosmic Rays and Implications for Their Source Candidates
• Ultrahigh Energy Nuclei Propagation in a Structured, Magnetized Universe
• Testing large-scale (an)isotropy of ultra-high energy cosmic rays
• Ultra-high energy cosmic rays from a finite number of point sources
• The footprint of large scale cosmic structure on the ultra-high energy cosmic ray distribution
• Light Nuclei solving Auger puzzles. The Cen-A imprint
• Clustering of ultra-high energy cosmic ray arrival directions on medium scales
• Neutrinos from active black holes, sources of ultra high energy cosmic rays
• Cuts and penalties: comment on "The clustering of ultra-high energy cosmic rays and their sources"
• Implications to Sources of Ultra-high-energy Cosmic Rays from their Arrival Distribution
• Super Heavy Dark Matter and UHECR Anisotropy at Low Energy
• Strong lensing probability in TeVeS theory
• Clustering properties of ultrahigh energy cosmic rays and the search for their astrophysical sources
• Statistics of cluster multiplicity and the nature of UHE cosmic ray sources
• Astrophysical interpretation of the medium scale clustering in the ultra-high energy sky

Cited by in corpus (12)

• Bounds on the density of sources of ultra-high energy cosmic rays from the Pierre Auger Observatory
• The Role of Structured Magnetic Fields on Constraining Properties of Transient Sources of Ultra-high-energy Cosmic Rays
• Does Galactic Magnetic Field Disturb the Correlation of the Highest Energy Cosmic Rays with their Sources?
• UHECR observations and lensing in the magnetic field of the Virgo cluster
• Propagation of Ultra-High-Energy Cosmic Ray Nuclei in Cosmic Magnetic Fields and Implications for Anisotropy Measurements
• Isotropy constraints on powerful sources of ultrahigh-energy cosmic rays at $10^{19}$ eV
• Identification of Patterns in Cosmic-Ray Arrival Directions using Dynamic Graph Convolutional Neural Networks
• Bounds on the origin of extragalactic ultrahigh energy cosmic rays from the IceCube neutrino observations
• Treasure Maps for Detections of Extreme Energy Cosmic Rays
• Multiscale autocorrelation function: a new approach to anisotropy studies
• Extended clustering analyses to constrain the deflection angular scale and source density of the ultra-high-energy cosmic rays
• Anisotropy studies with multiscale autocorrelation function