Dark matter and dark energy in galaxies and astrophysical objects

Abstract

I describe static configurations of dark matter coupled to the scalar field responsible for the dark energy of the Universe. The mass of the dark matter particles is a function of the scalar field. I discuss first the profile of the dark matter halos in galaxies. In the presence of a scalar field, the velocity of a massive object orbiting the galaxy is not of the order of the typical velocity of the dark matter particles, as in the conventional picture. Instead, it is reduced by a factor encoding the dependence of the dark matter mass on the scalar field. This has implications for dark matter searches. I also describe new solutions of the Einstein equations for compact objects composed of dark matter. The size of these objects can vary between microscopic scales and cosmological distances. I discuss the mass to radius relation and the similarities with conventional neutron stars and exotic astrophysical objects.