SZE Observables, Pressure Profiles and Center Offsets in Magneticum Simulation Galaxy Clusters

TL;DR

This study uses Magneticum simulations to analyze galaxy cluster pressure profiles, SZE signals, and center offsets, revealing significant variations, biases in hydrostatic mass estimates, and a new generalized NFW model that captures these trends.

Contribution

Introduces a new generalized NFW pressure profile model that accounts for mass and redshift variations, and analyzes SZE signal scatter and center offsets in simulated galaxy clusters.

Findings

Pressure profile shape varies with mass and redshift.

Hydrostatic equilibrium accounts for only 80% of pressure, biasing mass estimates.

Line-of-sight structure increases SZE scatter, especially in low-mass clusters.

Abstract

We present a detailed study of the galaxy cluster thermal \ac{sze} signal $Y$ and pressure profiles using {\it Magneticum} Pathfinder hydrodynamical simulations. With a sample of 50,000 galaxy clusters ($M_{\rm 500c}>1.4\times10^{14} \rm M_{\odot}$) 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 model that follows these trends. We show that the thermal pressure at $R_{\rm 500c}$ accounts for only 80~percent of the pressure required to maintain hydrostatic equilibrium, and therefore even idealized hydrostatic mass estimates would be biased at the 20~percent level. We compare the cluster \ac{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 ($\sigma_{\ln Y}\simeq 0.087$) 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 \ac{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 $\sim0.16$ at low masses. The scatter distribution is consistent with log-normal in all cases. We present a model of the offsets between the center of the gravitational potential and the \ac{sze} center that follows the variations with cluster mass and redshift.