Pressure of the hot gas in simulations of galaxy clusters
  We analyze the radial pressure profiles, the ICM clumping factor and the
Sunyaev-Zel'dovich (SZ) scaling relations of a sample of simulated galaxy
clusters and groups identified in a set of hydrodynamical simulations based on
an updated version of the TreePM-SPH GADGET-3 code. Three different sets of
simulations are performed: the first assumes non-radiative physics, the others
include, among other processes, AGN and/or stellar feedback. Our results are
analyzed as a function of redshift, ICM physics, cluster mass and cluster
cool-coreness or dynamical state. In general, the mean pressure profiles
obtained for our sample of groups and clusters show a good agreement with X-ray
and SZ observations. Simulated cool-core (CC) and non-cool-core (NCC) clusters
also show a good match with real data. We obtain in all cases a small (if any)
redshift evolution of the pressure profiles of massive clusters, at least back
to z=1. We find that the clumpiness of gas density and pressure increases with
the distance from the cluster center and with the dynamical activity. The
inclusion of AGN feedback in our simulations generates values for the gas
clumping ($\sqrt C_{\rho}\sim 1.2$ at $R_{200}$) in good agreement with recent
observational estimates. The simulated $Y_{SZ}-M$ scaling relations are in good
accordance with several observed samples, especially for massive clusters. As
for the scatter of these relations, we obtain a clear dependence on the cluster
dynamical state, whereas this distinction is not so evident when looking at the
subsamples of CC and NCC clusters.
