A Challenge to the Standard Cosmological Model

Abstract

We present the first joint analysis of catalogs of radio galaxies and quasars to determine whether 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 statistically 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 statistic that accounts for correlation between the found dipole amplitude and its directional offset from the CMB dipole, the null hypothesis is independently rejected by the radio galaxy and quasar samples with p-values of 8.9 × 10−3 and 1.2 × 10−5, respectively, corresponding to 2.6σ and 4.4σ significance. The joint significance, using sample-size-weighted Z-scores, is 5.1σ. 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. The consistency of the two dipoles improves if we boost to the CMB frame assuming its dipole to be fully kinematic, suggesting that cosmologically distant radio galaxies and quasars may have an intrinsic anisotropy in this frame.

The Clustering Properties of AGNs/Quasars in CatWISE2020 Catalog

“…We add that the clustering dipole magnitude expected with this bias and N(z) assuming ΛCDM is 0.81 × 10 −3 (i.e., C 1 = 0.91 × 10 −6 ). 12 However, notice that the dipole signal in galaxy count is largely from aberration and Doppler effects caused by local motion (Ellis & Baldwin 1984), and for CatWISE2020 the predicted value is 0.73 × 10 −2 (Secrest et al 2022).…”

Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Increasing Tension with the Standard Cosmological Model

“…While this behavior is difficult to explain in the standard model, it could be an indication that the particle rest frame of the Universe is not the same as that inferred from the dipole in the cosmic microwave background (CMB) radiation (see e.g., Kashlinsky et al 2008;Ma et al 2011;Kashlinsky & Atrio-Barandela 2022). Indeed, significant evidence that the CMB frame is not the rest frame of the Universe can also be seen in the analyses of the distribution of Quasars on the sky (Secrest et al 2021(Secrest et al , 2022Dam et al 2022). We should note that the flattening out of the curves in Fig.…”

Peculiar velocity effects on the Hubble constant from time-delay cosmography

“…Aberration of angles and Doppler shift then affect these number counts per unit solid angle in such a way that permits the extraction of the observer's peculiar velocity with respect to these sources. This has led to a number count dipole, which is well aligned with the CMB dipole but about 2 − 5 times as large as expected from 𝒗 dip and which has reached a ∼ 5𝜎 tension [14][15][16][17][18]. In [12], it was suggested that the redshift evolution of the population of sources may, at least partially, explain the discrepancy.…”

“…The authors of Ref. [18] reanalyzed the data of [14,15] and concluded that neither masking nor parameter evolution can fully explain the discrepancy, although the latter is subject to further assumptions. If the dominantly kinematic interpretation of this number count dipole is correct, it should show up in the correlations between the 𝑙 and 𝑙 ± 1 multipoles of the number counts, which require high-angular resolution surveys [20,21].…”