TY - JOUR

T1 - The growth of matter perturbations in some scalar-tensor de models

AU - GANNOUJI , RADOUANE

AU - Polarski, David

PY - 2008/5/1

Y1 - 2008/5/1

N2 - We consider asymptotically stable scalar-tensor dark energy (DE) models for which the equation of state parameter wDE tends to zero in the past. The viable models are of the phantom type today: however, this phantomness is milder than in general relativity if we take into account the varying gravitational constant when dealing with the SNIa data. We study further the growth of matter perturbations and we find a scaling behaviour on large redshifts which could provide an important constraint. In particular, the growth of matter perturbations on large redshifts in our scalar-tensor models is close to the standard behaviour , while it is substantially different for the best-fit model in general relativity for the same parametrization of the background expansion. As for the growth of matter perturbations on small redshifts, we show that in these models the parameter can take absolute values much larger than in models inside general relativity. Assuming a constant γ when γ′0 is large would lead to a poor fit of the growth function f. This provides another characteristic discriminative signature for these models.

AB - We consider asymptotically stable scalar-tensor dark energy (DE) models for which the equation of state parameter wDE tends to zero in the past. The viable models are of the phantom type today: however, this phantomness is milder than in general relativity if we take into account the varying gravitational constant when dealing with the SNIa data. We study further the growth of matter perturbations and we find a scaling behaviour on large redshifts which could provide an important constraint. In particular, the growth of matter perturbations on large redshifts in our scalar-tensor models is close to the standard behaviour , while it is substantially different for the best-fit model in general relativity for the same parametrization of the background expansion. As for the growth of matter perturbations on small redshifts, we show that in these models the parameter can take absolute values much larger than in models inside general relativity. Assuming a constant γ when γ′0 is large would lead to a poor fit of the growth function f. This provides another characteristic discriminative signature for these models.

KW - Cosmological perturbation theory

KW - Dark energy theory

UR - http://www.scopus.com/inward/record.url?scp=44449168197&partnerID=8YFLogxK

U2 - 10.1088/1475-7516/2008/05/018

DO - 10.1088/1475-7516/2008/05/018

M3 - Article

AN - SCOPUS:44449168197

VL - 2008

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

SN - 1475-7516

IS - 5

M1 - 018

ER -