%0 Journal Article
%T Consistency of the expansion of the Universe with density perturbations
%+ Laboratoire Charles Coulomb (L2C)
%A Gannouji, Radouane
%A Polarski, David
%< avec comité de lecture
%@ 1550-7998
%J Physical Review D
%I American Physical Society
%V 98
%N 8
%P 083533
%8 2018
%D 2018
%Z 1805.08230
%R 10.1103/PhysRevD.98.083533
%K Cosmology
%Z Physics [physics]/Astrophysics [astro-ph]
%Z Physics [physics]/General Relativity and Quantum Cosmology [gr-qc]Journal articles
%X 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 parameters can be constrained using background expansion data. We explore systematically the preferred region in this parameter space. Inside general relativity we obtain that models with a quasistatic growth index and γ1≈-0.02 are favored. We find further the lower bounds γ0≳0.53 and γ1≳-0.15 for models inside GR. Models outside GR having the same background expansion as ΛCDM and arbitrary γ(z) with γ0=γ0ΛCDM, satisfy Geff,0>G for γ1>γ1ΛCDM, and Geff,0<G for γ1<γ1ΛCDM. The first models will cross downwards the value Geff=G on very low redshifts z<0.3, while the second models will cross upwards Geff=G in the same redshift range. This makes the realization of such modified gravity models even more problematic.
%G English
%L hal-01815115
%U https://hal.science/hal-01815115
%~ CNRS
%~ L2C
%~ MIPS
%~ UNIV-MONTPELLIER
%~ UM-2015-2021