  Dynamical Chern-Simons gravity is an interesting extension of General
Relativity, which finds its way in many different contexts, including string
theory, cosmological settings and loop quantum gravity. In this theory, the
gravitational field is coupled to a scalar field by a parity-violating term,
which gives rise to characteristic signatures. Here we investigate how
Chern-Simons gravity would affect the quasi-circular inspiralling of a small,
stellar-mass object into a large non-rotating supermassive black hole, and the
accompanying emission of gravitational and scalar waves. We find the relevant
equations describing the perturbation induced by the small object, and we solve
them through the use of Green's function techniques. Our results show that for
a wide range of coupling parameters, the Chern-Simons coupling gives rise to an
increase in total energy flux, which translates into a fewer number of
gravitational-wave cycles over a certain bandwidth. For space-based
gravitational-wave detectors such as LISA, this effect can be used to constrain
the coupling parameter effectively.
