Dark fluid: A complex scalar field to unify dark energy and dark matter

In this article, we examine a model which proposes a common explanation for the presence of additional attractive gravitational effects—generally considered to be due to dark matter—in galaxies and in clusters, and for the presence of a repulsive effect at cosmological scales—generally taken as an indication of the presence of dark energy. We therefore consider the behavior of a so-called dark fluid based on a complex scalar field with a conserved $U(1)$-charge and associated to a specific potential, and show that it can at the same time account for dark matter in galaxies and in clusters, and agree with the cosmological observations and constraints on dark energy and dark matter.

Figure 1

Rotation curve of a generic spiral galaxy, in presence of a complex scalar field with a uniformly rotation phase accounting for dark matter. The solid line corresponds to an example of rotation curve provided by the complex scalar field plus the baryons, whereas the dashed line shows the contribution of the baryons only.

Figure 2

Cosmological evolution of the density of the scalar field dark fluid in comparison to the densities of baryonic matter and radiation.