Cosmological constraints on induced gravity dark energy models
Mario Ballardini, Fabio Finelli, Caterina Umiltà, Daniela Paoletti
Abstract
We study induced gravity dark energy models coupled with a simple monomial potential
∝
σ
n
and a positive exponent
n
. These simple potentials lead to viable dark energy models with a weak dependence on the exponent, which characterizes the accelerated expansion of the cosmological model in the asymptotic attractor, when ordinary matter becomes negligible. We use recent cosmological data to constrain the coupling
γ
to the Ricci curvature, under the assumptions that the scalar field starts at rest deep in the radiation era and that the gravitational constant in the Einstein equations is compatible with the one measured in a Cavendish-like experiment. By using
Planck
2015 data only, we obtain the 95 % CL bound
γ<0.0017
for
n=4
, which is further tightened to
γ<0.00075
by adding Baryonic Acoustic Oscillations (BAO) data. This latter bound improves by
∼30
% the limit obtained with the
Planck
2013 data and the same compilation of BAO data. We discuss the dependence of the
γ
and
G
˙
N
/
G
N
(z=0)
on
n
.