Probing ICM Physics with Gas Density Perturbations

The hot intracluster (ICM) medium is the dominant baryonic component of galaxy clusters. Many processes, from matter accretion and cluster mergers to AGN feedback and motions of galaxies, perturb the hot gas on a range of spatial scales. Imprinted on the X-ray images, the statistical properties of these perturbations at each scale can be measured providing new information about the ICM physics. I will present a summary of what we have learned so far with this analysis technique. In particular, I will discuss turbulence measurements, the effective equation of state of gas perturbations in regions dominated by AGN feedback, recent constraints on effective viscosity in the bulk intergalactic plasma. Challenges that we are currently facing and future perspectives will be briefly discussed at the end.