Enhancement of Dark Matter Abundance in Scalar-Tensor Dark Energy

In Scalar-Tensor theories of gravity, the expansion rate of the universe in the past may differ considerably from the standard one. After imposing the constraints coming from nucleosynthesis, CMB, type Ia supernovae, and solar system tests of General Relativity, we consider the expansion rate of the universe at WIMP decoupling, showing that it can lead to an enhancement of the dark matter relic density of some orders of magnitude with respect to the standard case. This effect may have a deep impact on most popular candidates for dark matter, as the supersymmetric neutralino.