Non-minimal coupling of scalar fields in the dark sector and generalization of the top-hat collapse

Abstract

In this article we propose a new way to handle interactions between two scalar fields, in the cosmological backdrop, where one scalar field oscillates rapidly in the cosmological time scale while the other one evolves without showing any periodic behavior. We have interpreted the rapidly oscillating scalar field as the dark matter candidate while the other scalar field is the canonical quintessence field or the non-canonical phantom field. A model of a generalized top-hat-like collapse is developed where the dark sector is composed of the aforementioned scalar fields. We show how the non-minimal coupling in the dark sector affects the gravitational collapse of a slightly overdense spherical patch of the universe. The results show that one can have both unclustered and clustered dark energy in such collapses, the result depends upon the magnitude of the non-minimal coupling strength.