Due to their late formation in cosmic history , clusters of galaxies are not fully in hydrostatic equilibrium and the gravitational pull of their mass at a given radius is expected not to be entirely balanced by the thermal gas pressure .
Turbulence may supply additional pressure , and recent ( X-ray and SZ ) hydrostatic mass reconstructions claim a pressure support of \sim 5 - 15 \% of the total pressure at R _ { 200 } .
In this work we show that , after carefully disentangling bulk from small-scale turbulent motions in high-resolution simulations of galaxy clusters , we can constrain which fraction of the gas kinetic energy effectively provides pressure support in the cluster ’ s gravitational potential .
While the ubiquitous presence of radial inflows in the cluster can lead to significant bias in the estimate of the non-thermal pressure support , we report that only a part of this energy effectively acts as a source of pressure , providing a support of the order of \sim 10 \% of the total pressure at R _ { 200 } .