  In interacting galaxies, strong tidal forces disturb the global morphology of
the progenitors and give birth to the long stellar, gaseous and dusty tails
often observed. In addition to this destructive effect, tidal forces can morph
into a transient, protective setting called compressive mode. Such modes then
shelter the matter in their midst by increasing its gravitational binding
energy. This thesis focuses on the study of this poorly known regime by
quantifying its properties thanks to numerical and analytical tools applied to
a spectacular merging system of two galaxies, commonly known as the Antennae
galaxies. N-body simulations of this pair yield compressive modes in the
regions where observations reveal a burst of star formation. Furthermore,
characteristic time- and energy scales of these modes match well those of
self-gravitating substructures such as star clusters and tidal dwarf galaxies.
These results suggest that the compressive modes of tidal fields plays an
important role in the formation and evolution of young clusters, at least in a
statistical sense, over a lapse of ~10 million years. Preliminary results from
simulations of stellar associations highlight the importance of embedding the
clusters in the evolving background galaxies to account precisely for their
morphology and internal evolution.
