SZE observables, pressure profiles and centre offsets in Magneticum simulation galaxy clusters

We present a detailed study of the galaxy cluster thermal Sunyaev-Zel'dovich effect (SZE) signal Y and pressure profiles using Magneticum Pathfinder hydrodynamical simulations. With a sample of 50 000 galaxy clusters (M500c > 1.4 × 1014 M☉) out to z = 2, we find significant variations in the shape of the pressure profile with mass and redshift and present a new generalized NFW (Navarro-Frenk-White) model that follows these trends. We show that the thermal pressure at R500c accounts for only 80 per cent of the pressure required to maintain hydrostatic equilibrium, and therefore even idealized hydrostatic mass estimates would be biased at the 20 per cent level. We compare the cluster SZE signal extracted from a sphere with different virial-like radii, a virial cylinder within a narrow redshift slice and the full light-cone, confirming small scatter (σln Y ≃ 0.087) in the sphere and showing that structure immediately surrounding clusters increases the scatter and strengthens non-self-similar redshift evolution in the cylinder. Uncorrelated large-scale structure along the line of sight leads to an increase in the SZE signal and scatter that is more pronounced for low-mass clusters, resulting in non-self-similar trends in both mass and redshift and a mass-dependent scatter, that is, ∼0.16 at low masses. The scatter distribution is consistent with lognormal in all cases. We present a model of the offsets between the centre of the gravitational potential and the SZE centre that follows the variations with cluster mass and redshift.