Correlations between ultrahigh energy cosmic rays and infrared-luminous galaxies

We confirm the ultrahigh energy cosmic ray (UHECR) horizon established by the Pierre Auger Observatory using the heterogeneous Véron-Cetty- Véron (VCV) catalog of active galactic nuclei by performing a redshift-angle-IR luminosity scan using point-source catalog with redshift (PSCz) galaxies having infrared luminosity greater than 10¹⁰ L _⊙. The strongest correlation - for z < 0.016, ψ = 21, and L _ir ≥ 10^10.5 L _⊙ - arises in fewer than 0.3% of scans with isotropic source directions. When we apply a penalty for using the UHECR energy threshold that was tuned to maximize the correlation with VCV, the significance degrades to 1.1%. Since the PSCz catalog is complete and volume-limited for these parameters, this suggests that the UHECR horizon discovered by the Pierre Auger Observatory is not an artifact of the incompleteness and other idiosyncrasies of the VCV catalog. The strength of the correlation between UHECRs and the nearby highest-IR-luminosity PSCz galaxies is stronger than in about 90% of trials with scrambled luminosity assignments for the PSCz galaxies. If confirmed by future data, this result would indicate that the sources of UHECRs are more strongly associated with luminous IR galaxies than with ordinary, lower IR luminosity galaxies.