## Abstract

We consider the linear growth of matter perturbations in various dark energy (DE) models. We show the existence of a constraint valid at z = 0 between the background and dark energy parameters and the matter perturbations growth parameters. For ΛCDM γ_{0}
^{′} ≡ frac(d γ, d z) |_{0} lies in a very narrow interval - 0.0195 ≤ γ_{0}
^{′} ≤ - 0.0157 for 0.2 ≤ Ω_{m, 0} ≤ 0.35. Models with a constant equation of state inside General Relativity (GR) are characterized by a quasi-constant γ_{0}
^{′}, for Ω_{m, 0} = 0.3 for example we have γ_{0}
^{′} ≈ - 0.02 while γ_{0} can have a nonnegligible variation. A smoothly varying equation of state inside GR does not produce either | γ_{0}
^{′} | > 0.02. A measurement of γ (z) on small redshifts could help discriminate between various DE models even if their γ_{0} is close, a possibility interesting for DE models outside GR for which a significant γ_{0}
^{′} can be obtained.

Original language | English |
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Pages (from-to) | 439-443 |

Number of pages | 5 |

Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |

Volume | 660 |

Issue number | 5 |

DOIs | |

State | Published - 6 Mar 2008 |