Eccentric binary black hole mergers in globular clusters hosting
  intermediate-mass black holes
  Globular clusters (GCs) may harbour intermediate-mass black holes (IMBHs) at
their centres. In these dynamically active environments stellar-mass black
holes (SBHs) sink to the center soon after formation, due to dynamical friction
and start interacting among themselves and with the central IMBH. Likely, some
of the SBHs will form bound systems with the IMBH. A fraction of those will be
triple systems composed of binary SBHs and the IMBH acting as a third distant
perturber. If the SBH binary orbit is sufficiently inclined it can develop
Lidov-Kozai (LK) oscillations, which can drive the system to high
eccentricities and eventually to a merger due to gravitational wave (GW)
emission on short timescales. In this work, we focus on the dynamics of the
IMBH-SBH-SBH triples and illustrate that these systems can be possible sources
of GWs. A distinctive signature of this scenario is that a considerable
fraction of these mergers are highly eccentric when entering the LIGO band
($10$ Hz). Assuming that $\sim 20\%$ of GCs host IMBHs and a GC density in the
range $n_{_{\rm GC}}=0.32$-$2.31\,\mathrm{Mpc}^{-3}$, we have estimated a rate
$\Gamma=0.06$-$0.46\,\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$ of these events. This
suggests that dynamically-driven binary SBH mergers in this scenario could
contribute to the merger events observed by LIGO/VIRGO. Full $N$-body
simulations of GCs harbouring IMBHs are highly desirable to give a more precise
constrain on this scenario.
