Repeated Bursts from Relativistic Scattering of Compact Objects in
  Galactic Nuclei
  Galactic nuclei are densely populated by stellar mass compact objects such as
black holes and neutron stars. Bound, highly eccentric binaries form as a
result of gravitational wave (GW) losses during close flybys between these
objects. We study the evolution of these systems using 2.5 and 3.5 order
post-Newtonian equations of motion. The GW signal consists of many thousand
repeated bursts (RB) for minutes to days (depending on the impact parameter and
masses), followed by a powerful GW chirp and an eccentric merger. We show that
a significant signal to noise ratio (SNR) accumulates already in the RB phase,
corresponding to a detection limit around 200-300 Mpc and 300--600 Mpc for
Advanced LIGO for an average orientation BH/NS or BH/BH binary, respectively.
The theoretical errors introduced by the inaccuracy of the PN templates are
typically much less severe for the RB phase than in the following eccentric
merger. The GW signal in the RB phase is broadband; we show that encounters
involving intermediate mass black holes are detectable in multiple frequency
bands coincidentally using LIGO and LISA.
