Note on bigravity and dark matter

We show that a class of bigravity theories contain solutions describing dark matter. A particular member of this class is also shown to be equivalent to the Eddington-Born-Infeld gravity, recently proposed as a candidate for dark matter. Bigravity theories also have cosmological de Sitter backgrounds and we find solutions interpolating between matter and acceleration eras.

Figure 1

Stability regions for the proportional vacuum solution (PV) and the nonproportional ones (NPV). In the left the value of ${\alpha }_0=0.5$ is fixed. In the right $\alpha =0.9$ is fixed.