Characterizing the bulk and turbulent gas motions in galaxy clusters
  The most massive halos of matter in the Universe grow via accretion and
merger events throughout cosmic times. These violent processes generate shocks
at many scales and induce large-scale bulk and turbulent motions. These
processes inject kinetic energy at large scales, which is transported to the
viscous dissipation scales, contributing to the overall heating and
virialisation of the halo, and acting as a source of non-thermal pressure in
the intra-cluster medium. Characterizing the physical properties of these gas
motions will help us to better understand the assembly of massive halos, hence
the formation and the evolution of these large-scale structures. We base this
characterization on the study of the X-ray and Sunyaev-Zel'dovich effect
brightness fluctuations. Our work relies on three complementary samples
covering a wide range of redshifts, masses and dynamical states of clusters. We
present the results of our X-ray analysis for the low redshift sample, X-COP,
and a subsample of higher redshift clusters. We investigate the derived
properties according to the dynamical state of our clusters, and the
possibility of a self-similar behaviour based on the reconstructed gas motions
power-spectra and the correlation with various morphological indicators.
