The distribution of radio galaxies and quasars that are observed is inconsistent the the Standard Model of Cosmology which asserts that at a sufficiently large scale the universal should look essentially the same in all directions aside from a correction based upon our vantage point of observation.
We present the first joint analysis of catalogs of radio galaxies and quasars to determine if their sky distribution is consistent with the standard ΛCDM model of cosmology. This model is based on the cosmological principle, which asserts that the universe is isotropic and homogeneous on large scales, so the observed dipole anisotropy in the cosmic microwave background (CMB) must be attributed to our local peculiar motion.
We test the null hypothesis that there is a dipole anisotropy in the sky distribution of radio galaxies and quasars consistent with the motion inferred from the CMB, as is expected for cosmologically distant sources. Our two samples, constructed respectively from the NRAO VLA Sky Survey and the Wide-field Infrared Survey Explorer, are systematically independent and have no shared objects.
Using a completely general, two dimensional definition of the p-value that accounts for correlation between the found dipole amplitude and its directional offset from the CMB dipole, the null hypothesis is independently rejected with p=7.9×10^−3 and p=9.9×10^−6 for the radio galaxy and quasar samples, respectively, corresponding to 2.7σ and 4.4σ significance. The joint significance, using sample size-weighted Z-scores, is 5.2σ. We show that the radio galaxy and quasar dipoles are consistent with each other and find no evidence for any frequency dependence of the amplitude.