Late Inspiral and Merger of Binary Black Holes in Scalar-Tensor Theories
  of Gravity
  Gravitational wave observations will probe non-linear gravitational
interactions and thus enable strong tests of Einstein's theory of general
relativity. We present a numerical relativity study of the late inspiral and
merger of binary black holes in scalar-tensor theories of gravity. We consider
black hole binaries in an inhomogeneous scalar field, specifically binaries
inside a scalar field bubble, in some cases with a potential. We calculate the
emission of dipole radiation. We also show how these configurations trigger
detectable differences between gravitational waves in scalar-tensor gravity and
the corresponding waves in general relativity. We conclude that, barring an
external mechanism to induce dynamics in the scalar field, scalar-tensor
gravity binary black holes alone are not capable of awaking a dormant scalar
field, and are thus observationally indistinguishable from their general
relativistic counterparts.
