  In this thesis we study several dynamical processes involving black holes in
four and higher dimensions. First, using perturbative techniques, we compare
the massless and massive scalar radiation emitted by a particle radially
infalling into a Schwarzchild black hole. We show that the late-time waveform
of massive scalar perturbations is dominated by a universal oscillatory
decaying tail, which appears due to curvature effects. We also show that the
energy spectrum is in perfect agreement with a ZFL calculation once no-hair
properties of black holes are taken into account. In the second part, we study
the phenomenon of superradiance in higher dimensions and conjecture that the
maximum energy extracted from a rotating black hole can be understood in terms
of the ergoregion proper volume. We then study some consequences of
superradiance in the dynamics of moons orbiting around higher-dimensional
rotating black holes. In four-dimensional spacetime, moons around black holes
generate low-amplitude tides, and the energy extracted from the hole's rotation
is always smaller than the gravitational radiation lost to infinity. We show
that in dimensions larger than five the energy extracted from the black hole
through superradiance is larger than the energy carried out to infinity. Our
results lend strong support to the conjecture that tidal acceleration is the
rule, rather than the exception, in higher dimensions. Superradiance dominates
the energy budget and moons "outspiral"; for some particular orbital frequency,
the energy extracted at the horizon equals the energy emitted to infinity and
"floating orbits" generically occur. We give an interpretation of this
phenomenon in terms of the membrane paradigm and of tidal acceleration due to
energy dissipation across the horizon.
