Rastall cosmology and the $\Lambda \mathrm{CDM}$ model

Rastall’s theory is based on the nonconservation of the energy-momentum tensor. We show that, in this theory, if we introduce a two-fluid model, one component representing vacuum energy whereas the other pressureless matter (e.g. baryons plus cold dark matter), the cosmological scenario is the same as for the $\Lambda \mathrm{CDM}$ model, both at background and linear perturbation levels, except for one aspect: now dark energy may cluster. We speculate that this can lead to a possibility of distinguishing the models at the nonlinear perturbation level.

Figure 1

Probability density function (PDF) of ${\omega }_e$.