The Tolman-Oppenheimer-Volkoff equations in unified models of dark matter and dark energy

In this thesis we will work on scalar field models for dark matter and dark energy. In particular, we will study unified haloes by means of a static and spherically symmetric metric which leads to the anisotropic Tolman-Oppenheimer-Volkoff (TOV) equation. In this framework, we will develop a procedure which allows us to compute an unified density profile starting from a generic cold dark matter one, or, equivalently, from its rotation velocity. In particular, we will focus our attention on finding a suitable Lagrangian of a given type, which provides us with a microscopical description of the problem.