Unveiling the Galileon in a three-body system : scalar and gravitational
  wave production
  We consider the prospect of detecting cubic Galileons through their imprint
on gravitational wave signals from a triple system. Namely, we consider a
massive Black Hole (BH) surrounded by a binary system of two smaller BHs. We
assume that the three BHs acquire a conformal coupling to the scalar field
whose origin could be due to cosmology or to the galactic environment. In this
case, the massive BH has a Vainshtein radius which englobes the smaller ones
and suppresses the scalar effects on the motion of the binary system. On the
other hand the two binaries can be outside each other's redressed Vainshtein
radius calculated in the background of the central BH, allowing for a
perturbative treatment of their dynamics. Despite the strong Vainshtein
suppression, we find that the scalar effects on the binary system are slightly
enhanced with respect to the static case and a significant amount of power can
be emitted in the form of the Galileon scalar field, hence actively
participating in the inspiralling phase. We compute the modification to the GW
phase and show that it can lead to a detectable signal for large enough
effective scalar coupling.
