  The direct detection of gravitational waves offers an exciting new window
onto our Universe. At the same time, multiple observational evidence and
theoretical considerations motivate the presence of physics beyond the Standard
Model. In this thesis, we explore new ways of probing particle physics in the
era of gravitational-wave astronomy. We focus on the signatures of ultralight
bosons on the gravitational waves emitted by binary systems, demonstrating how
binary black holes are novel detectors of this class of dark matter. We also
discuss probes of other types of new physics through their finite-size imprints
on gravitational waveforms, and examine the extent to which current
template-bank searches could be used to detect these signals. In the first two
chapters of this thesis, we review several aspects of gravitational-wave
physics and particle physics at the weak coupling frontier; we hope the reader
would find these reviews helpful in delving further into the literature and in
their research.
