Large-Scale Structure Formation: from the first non-linear objects to
  massive galaxy clusters
  The large-scale structure of the Universe formed from initially small
perturbations in the cosmic density field, leading to galaxy clusters with up
to 10^15 Msun at the present day. Here, we review the formation of structures
in the Universe, considering the first primordial galaxies and the most massive
galaxy clusters as extreme cases of structure formation where fundamental
processes such as gravity, turbulence, cooling and feedback are particularly
relevant. The first non-linear objects in the Universe formed in dark matter
halos with 10^5-10^8 Msun at redshifts 10-30, leading to the first stars and
massive black holes. At later stages, larger scales became non-linear, leading
to the formation of galaxy clusters, the most massive objects in the Universe.
We describe here their formation via gravitational processes, including the
self-similar scaling relations, as well as the observed deviations from such
self-similarity and the related non-gravitational physics (cooling, stellar
feedback, AGN). While on intermediate cluster scales the self-similar model is
in good agreement with the observations, deviations from such self-similarity
are apparent in the core regions, where numerical simulations do not reproduce
the current observational results. The latter indicates that the interaction of
different feedback processes may not be correctly accounted for in current
simulations. Both in the most massive clusters of galaxies as well as during
the formation of the first objects in the Universe, turbulent structures and
shock waves appear to be common, suggesting them to be ubiquitous in the
non-linear regime.
