Generation of gravitational waves and tidal disruptions in clumpy
  galaxies
  Obtaining a better understanding of intermediate-mass black holes (IMBHs) is
crucial, as their properties could shed light on the origin and growth of their
supermassive counterparts. Massive star-forming clumps, which are present in a
large fraction of massive galaxies at $z \sim$ 1-3, are amongst the venues
wherein IMBHs could reside. We perform a series of Fokker-Planck simulations to
explore the occurrence of tidal disruption (TD) and gravitational wave (GW)
events about an IMBH in a massive star-forming clump, modelling the latter so
that its mass ($10^8 \,{\rm M}_{\odot}$) and effective radius ($100$ pc) are
consistent with the properties of both observed and simulated clumps. We find
that the TD and GW event rates are in the ranges $10^{-6}$-$10^{-5}$ and
$10^{-8}$-$10^{-7}$ yr$^{-1}$, respectively, depending on the assumptions for
the initial inner density profile of the system ($\rho \propto r^{-2}$ or
$\propto r^{-1}$) and the initial mass of the central IMBH ($10^5$ or
$10^3\,{\rm M}_{\odot}$). By integrating the GW event rate over $z$ = 1-3, we
expect that the Laser Interferometer Space Antenna will be able to detect
$\sim$2 GW events per yr coming from these massive clumps; the intrinsic rate
of TD events from these systems amounts instead to a few $10^3$ per yr, a
fraction of which will be observable by, e.g. the Square Kilometre Array and
the Advanced Telescope for High Energy Astrophysics. In conclusion, our results
support the idea that the forthcoming GW and electromagnetic facilities may
have the unprecedented opportunity of unveiling the lurking population of
IMBHs.
