Piercing the Vainshtein screen with anomalous gravitational wave speed:
  Constraints on modified gravity from binary pulsars
  By using observations of the Hulse-Taylor pulsar we constrain the
gravitational wave (GW) speed to the level of $10^{-2}$. We apply this result
to scalar-tensor theories that generalize Galileon 4 and 5 models, which
display anomalous propagation speed and coupling to matter for GWs. We argue
that this effect survives conventional screening due to the persistence of a
scalar field gradient inside virialized overdensities, which effectively
"pierces" the Vainshtein screening. In specific branches of solutions, our
result allows to directly constrain the cosmological couplings in the effective
field theory of dark energy formalism.
