Agegraphic dark energy: growth index and cosmological implications
  We study the main cosmological properties of the agegraphic dark energy model
at the expansion and perturbation levels. Initially, using the latest
cosmological data we implement a joint likelihood analysis in order to
constrain the cosmological parameters. Then we test the performance of the
agegraphic dark energy model at the perturbation level and we define its
difference from the usual $\Lambda$CDM model. Within this context, we verify
that the growth index of matter fluctuations depends on the choice of the
considered agegraphic dark energy (homogeneous or clustered). In particular,
assuming a homogeneous agegraphic dark energy we find, for the first time, that
the asymptotic value of the growth index is $\gamma \approx 5/9$, which is
close to that of the usual $\Lambda$ cosmology, $\gamma^{(\Lambda)} \approx
6/11$. Finally, if the distribution of dark energy is clustered then we obtain
$\gamma \approx 1/2$ which is $\sim 8\%$ smaller than that of the $\Lambda$CDM
model.
