Astrophysical interpretation of the medium scale clustering in the ultrahigh energy sky

2007/06/30 by A. Cuoco, G. Miele, Gennaro Miele +2
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Auger #Cluster analysis #Cosmic ray #Dark Matter and Cosmic Phenomena #Galaxy #Galaxy cluster #Physics #Radio Astronomy Observations and Technology #Redshift #Sky #Statistics #Ultra-high-energy cosmic ray #astro-ph #hep-ph

paper · pdf · doi:10.1016/j.physletb.2007.12.054

published as Phys.Lett.B660:307-314,2008 · 10 pages, 7 figures; one reference added

openalex publication_date 2008/01/17 · arxiv created 2008/02/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We compare the clustering properties of the combined dataset of ultra-high energy cosmic rays events, reported by the AGASA, HiRes, Yakutsk and SUGAR Collaborations, with a catalogue of galaxies of the local universe (redshift z≲0.06). We find that the data reproduce particularly well the clustering properties of the nearby universe within z≲0.02. There is no statistically significant cross-correlation between data and structures, although intriguingly the nominal cross-correlation chance probability drops from O(50%) to O(10%) using the catalogue with a smaller horizon. Also, we discuss the impact on the robustness of the results of deflections in some galactic magnetic field models used in the literature. These results suggest a relevant role of magnetic fields (possibly extragalactic ones, too) and/or possibly some heavy nuclei fraction in the UHECRs. The importance of a confirmation of these hints (and of some of their implications) by Auger data is emphasized.

Citations

• Supercluster Magnetic Fields and Anisotropy of Cosmic Rays above 10**(19) eV
• The intergalactic propagation of ultra-high energy cosmic ray nuclei
• Studies of clustering in the arrival directions of cosmic rays detected at the Pierre Auger Observatory above 10 EeV
• Study of the Cosmic Ray Composition above 0.4 EeV using the Longitudinal Profiles of Showers observed at the Pierre Auger Observatory
• Clustering of ultra-high energy cosmic ray arrival directions on medium scales
• On the ultrahigh energy cosmic ray horizon
• First hints of large scale structures in the ultrahigh energy sky?
• Correlation function of ultrahigh-energy cosmic rays favors point sources
• Mapping deflections of extragalactic ultrahigh-energy cosmic rays in magnetohydrodynamic simulations of the local universe
• The toes of the ultra high energy cosmic ray spectrum