Ref HAL: hal-00430271_v1
Ref Arxiv: 0809.3374
DOI: 10.1088/1475-7516/2009/02/034
WoS: 000263824100034
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
113 Citations
Résumé:

We consider the linear growth of matter perturbations on low redshifts insome $f(R)$ dark energy (DE) models. We discuss the definition of dark energy(DE) in these models and show the differences with scalar-tensor DE models. Forthe $f(R)$ model recently proposed by Starobinsky we show that the growthparameter $\gamma_0\equiv \gamma(z=0)$ takes the value $\gamma_0\simeq 0.4$ for$\Omega_{m,0}=0.32$ and $\gamma_0\simeq 0.43$ for $\Omega_{m,0}=0.23$, allowingfor a clear distinction from $\Lambda$CDM. Though a scale-dependence appears inthe growth of perturbations on higher redshifts, we find no dispersion for$\gamma(z)$ on low redshifts up to $z\sim 0.3$, $\gamma(z)$ is alsoquasi-linear in this interval. At redshift $z=0.5$, the dispersion is stillsmall with $\Delta \gamma\simeq 0.01$. As for some scalar-tensor models, wefind here too a large value for $\gamma'_0\equiv \frac{d\gamma}{dz}(z=0)$,$\gamma'_0\simeq -0.25$ for $\Omega_{m,0}=0.32$ and $\gamma'_0\simeq -0.18$ for$\Omega_{m,0}=0.23$. These values are largely outside the range found for DEmodels in General Relativity (GR). This clear signature provides a powerfulconstraint on these models.