First hints of large scale structures in the ultra-high energy sky?

Abstract

The result of the recent publication [M. Kachelriess and D. V. Semikoz Astropart. Phys. 26, 10 (2006)] of a broad maximum around 25 degrees in the two-point autocorrelation function of ultra-high energy cosmic ray arrival directions has been intriguingly interpreted as the first imprint of the large scale structures (LSS) of baryonic matter in the near universe. We analyze this suggestion in light of the clustering properties expected from the PSCz astronomical catalogue of LSS. The chance probability of the signal is consistent within 2 sigma with the predictions based on the catalogue. No evidence for a significant cross-correlation of the observed events with known overdensities in the LSS is found, which may be due to the role of the galactic and extragalactic magnetic fields, and is however consistent with the limited statistics. The larger statistics to be collected by the Pierre Auger Observatory is needed to answer definitely the question.

arXiv comment5 pages, 3 figures. Slightly enlarged discussion, clarifications added, results unchanged. Matches published version

References in corpus (7)

• The PSCz Catalogue
• Dip in UHECR spectrum as signature of proton interaction with CMB
• Study of Small-Scale Anisotropy of Ultrahigh Energy Cosmic Rays Observed in Stereo by HiRes
• The Galactic magnetic field as spectrograph for ultra-high energy cosmic rays
• On the ultra-high energy cosmic ray horizon
• The footprint of large scale cosmic structure on the ultra-high energy cosmic ray distribution
• Clustering of ultra-high energy cosmic ray arrival directions on medium scales

Cited by in corpus (8)

• The Signature of Large Scale Structures on the Very High Energy Gamma-Ray Sky
• UHECR observations and lensing in the magnetic field of the Virgo cluster
• Clustering properties of ultrahigh energy cosmic rays and the search for their astrophysical sources
• Search for single sources of ultra high energy cosmic rays on the sky
• Search for clustering of ultra high energy cosmic rays from the Pierre Auger Observatory
• Astrophysical interpretation of the medium scale clustering in the ultra-high energy sky
• Multiscale autocorrelation function: a new approach to anisotropy studies
• Anisotropy studies with multiscale autocorrelation function