The growth of density perturbations in the last ∼10 billion years from tomographic large-scale structure data
Carlos García-García, Jaime Ruiz-Zapatero, David Alonso, Emilio Bellini, Pedro G. Ferreira, Eva-Maria Mueller, Andrina Nicola, P. Ruiz‐Lapuente
Abstract
In order to investigate the origin of the ongoing tension between the amplitude\nof matter fluctuations measured by weak lensing experiments at low redshifts and the value\ninferred from the cosmic microwave background anisotropies, we reconstruct the evolution of\nthis amplitude from z ∼ 2 using existing large-scale structure data. To do so, we decouple\nthe linear growth of density inhomogeneities from the background expansion, and constrain\nits redshift dependence making use of a combination of 6 different data sets, including cosmic shear, galaxy clustering and CMB lensing. We analyze these data under a consistent\nharmonic-space angular power spectrum-based pipeline. We show that current data constrain the amplitude of fluctuations mostly in the range 0.2 < z < 0.7, where it is lower than\npredicted by Planck. This difference is mostly driven by current cosmic shear data, although\nthe growth histories reconstructed from different data combinations are consistent with each\nother, and we find no evidence of systematic deviations in any particular experiment. In\nspite of the tension with Planck, the data are well-described by the ΛCDM model, albeit\nwith a lower value of S8 ≡ σ8(Ωm/0.3)0.5\n. As part of our analysis, we find constraints on\nthis parameter of S8 = 0.7781 ± 0.0094 (68% confidence level), reaching almost percent-level\nerrors comparable with CMB measurements, and 3.4σ away from the value found by Planck.