Is there concordance within the concordance $Λ$CDM model?

Abstract

We use a complete and rigorous statistical indicator to measure the level of concordance between cosmological data sets, without relying on the inspection of the marginal posterior distribution of some selected parameters. We apply this test to state of the art cosmological data sets, to assess their agreement within the $Λ$CDM model. We find that there is a good level of concordance between all the experiments with one noticeable exception. There is substantial evidence of tension between the CMB, temperature and polarization, measurements of the Planck satellite and the data from the CFHTLenS weak lensing survey even when applying ultra conservative cuts. These results robustly point toward the possibility of having unaccounted systematic effects in the data, an incomplete modelling of the cosmological predictions or hints toward new physical phenomena.

Figures (2)

• Figure 1: The Data Concordance Test (DCT) performed on all the independent couples of the cosmological data sets described in the text. The shaded region highlights the values of $\mathcal{C}$ that point toward disagreement between data sets. The error bars represent the uncertainty associated with the nested sampling computation of the evidence.
• Figure 2: The marginalized joint posterior for $\Omega_m$ and the amplitude of the linear power spectrum on the scale of $8\,h^{-1}\,\hbox{Mpc}$ for different data sets, as shown in legend. The darker and lighter shades correspond respectively to the $68\%$ C.L. and the $95\%$ C.L. regions.