Structure Formation in Generalized Rastall Gravity

Understand

Recently a modified version of Rastall theory of gravity has been introduced in which a varying coupling parameter could act as dark energy (DE) and thus, it can be held responsible for the current accelerated expansion of the Universe.

• Motivated by this modification, we study here the evolution of linear and non-linear perturbations in the matter content of the Universe, utilizing spherically symmetric top-hat collapse scenario.
• The exact solutions we obtain in linear regime show that as the Universe evolves, matter density perturbations grow and reach a maximum value at a certain redshift after which these perturbations start decreasing towards a finite positive value at the present time.
• Depending on model parameters, exact oscillatory solutions can be also found representing that matter perturbations could experience either overdense and underdense regions during the dynamical evolution of the Universe.