Consistency of the expansion of the Universe with density perturbations

摘要: Assuming a simple form for the growth index γ(z) depending on two parameters γ0≡γ(z=0) and γ1≡γ′(z=0), we show that these can be constrained using background expansion data. We explore systematically preferred region in this parameter space. Inside general relativity obtain models with quasistatic γ1≈-0.02 are favored. find further lower bounds γ0≳0.53 γ1≳-0.15 inside GR. Models outside GR having same as ΛCDM arbitrary γ0=γ0ΛCDM, satisfy Geff,0>G γ1>γ1ΛCDM, Geff,0