Forecasts for Low Spin Black Hole Spectroscopy in Horndeski Gravity
  We investigate the prospect of using black hole spectroscopy to constrain the
parameters of Horndeski gravity through observations of gravitational waves
from perturbed black holes. We study the gravitational waves emitted during
ringdown from black holes without hair in Horndeski gravity, demonstrating the
qualitative differences between such emission in General Relativity and
Horndeski theory. In particular, Quasi-Normal Mode frequencies associated with
the scalar field spectrum can appear in the emitted gravitational radiation.
Analytic expressions for error estimates for both the black hole and Horndeski
parameters are calculated using a Fisher Matrix approach, with constraints on
the `effective mass' of the Horndeski scalar field of order $\sim
10^{-17}$eV$c^{-2}$ or tighter being shown to be achievable in some scenarios.
Estimates for the minimum signal-noise-ratio required to observe such a signal
are also presented.
