Gravitational Origin of Dark Matter
  Observational evidence for the existence of Dark Matter is limited to its
gravitational effects. The extensive program for dedicated searches has yielded
null results so far, challenging the most popular models. Here we propose that
this is the case because the very existence of cold Dark Matter is a
manifestation of gravity itself. The consistent bimetric theory of gravity, the
only known ghost-free extension of General Relativity involving a massless and
a massive spin-2 field, automatically contains a perfect Dark Matter candidate.
We demonstrate that the massive spin-2 particle can be heavy, stable on
cosmological scales, and that it interacts with matter only through a
gravitational type of coupling. Remarkably, these features persist in the same
region of parameter space where bimetric theory satisfies the current gravity
tests. We show that the observed Dark Matter abundance can be generated via
freeze-in and suggest possible particle physics and gravitational signatures of
our bimetric Dark Matter model.
