Résumé
Using redshift space distortion data, we perform model-independent reconstructions of the growth history of matter inhomogeneity in the expanding Universe using two methods: crossing statistics and Gaussian processes. We then reconstruct the corresponding history of the Universe background expansion and fit it to Type Ia supernovae data, putting constraints on (Ω_m, 0, σ_8, 0). The results obtained are consistent with the concordance flat-ΛCDM model and General Relativity as the gravity theory given the current quality of the inhomogeneity growth data.