The growth of density perturbations in the last ∼10 billion years from tomographic large-scale structure data

In order to investigate the origin of the ongoing tension between the amplitude of matter fluctuations measured by weak lensing experiments at low redshifts and the value inferred from the cosmic microwave background anisotropies, we reconstruct the evolution of this amplitude from z similar to 2 using existing large-scale structure data. To do so, we decouple the linear growth of density inhomogeneities from the background expansion, and constrain its redshift dependence making use of a combination of 6 different data sets, including cos-mic shear, galaxy clustering and CMB lensing. We analyze these data under a consistent harmonic-space angular power spectrum-based pipeline. We show that current data con-strain the amplitude of fluctuations mostly in the range 0.2 < z < 0.7, where it is lower than predicted by Planck. This difference is mostly driven by current cosmic shear data, although the growth histories reconstructed from different data combinations are consistent with each other, and we find no evidence of systematic deviations in any particular experiment. In spite of the tension with Planck, the data are well-described by the ACDM model, albeit with a lower value of S8 -Sigma 8(Qm/0.3)0.5. As part of our analysis, we find constraints on this parameter of S8 = 0.7781 +/- 0.0094 (68% confidence level), reaching almost percent-level errors comparable with CMB measurements, and 3.4 Sigma away from the value found by Planck.

Automated summary

The study reconstructs the evolution of matter fluctuations amplitude from redshift 2 to low redshifts using existing large-scale structure data, showing that the current data mainly constrain the fluctuations amplitude in the range of 0.2 < z < 0.7, which is lower than predicted by Planck. However, the data are well-described by the ACDM model despite the tension with Planck, and constraints on the parameter S8 reach almost percent-level errors comparable with CMB measurements, deviating 3.4 Sigma away from the value found by Planck.