Probing Cosmic Strings with Gravitational-Wave Fringe
  Cosmic strings are important remnants of early-Universe phase transitions. We
show that they can be probed by Gravitational Waves (GWs) from compact binary
mergers. If such chirping GW passes by a cosmic string, it is gravitationally
lensed and left with a characteristic signal of the lensing -- the GW fringe.
It is observable naturally through the frequency chirping of GWs. This allows
to probe cosmic strings with small tension $\Delta = 8\pi G \mu = 10^{-6}
\text{ -- } 10^{-10}$, just below the current constraint, at high-frequency
LIGO-band and mid-band detectors. Although its detection rates are estimated to
be small, even a single detection can be used to identify a cosmic string.
Contrary to the stochastic GW produced from loop decays only in local $U(1)$
models, the GW fringe can directly probe straight strings model independently.
This is also complementary to the existing probes with the strong lensing of
light.
