An exploration of the properties of cluster profiles for the thermal and kinetic Sunyaev-Zel'dovich effects

TL;DR

This paper investigates the properties of electron pressure and density profiles in galaxy clusters using hydrodynamical simulations, revealing dependencies on halo concentration and mass, and providing parametric models for cosmological analysis.

Contribution

It introduces new insights into cluster assembly bias and mass-dependent pressure profiles, offering parametric formulas for use in future CMB studies.

Findings

Cluster properties depend strongly on halo concentration.

Lower mass halos exhibit lower pressure than previously thought.

Profiles evolve with redshift and halo mass, influenced by feedback processes.

Abstract

With the advent of high-resolution, low-noise CMB measurements, the ability to extract cosmological information from thermal Sunyaev-Zel'dovich effect and kinetic Sunyaev-Zel'dovich effect will be limited not by statistical uncertainties but rather by systematic and theoretical uncertainties. The theoretical uncertainty is driven by the lack of knowledge about the electron pressure and density. Thus we explore the electron pressure and density distributions in the IllustrisTNG hydrodynamical simulations, and we demonstrate that the cluster properties exhibit a strong dependence on the halo concentration -- providing some of the first evidence of cluster assembly bias in the electron pressure and density. Further, our work shows evidence for a broken power-law mass dependence, with lower pressure in lower mass halos than previous work and a strong evolution with mass of the radial correlations in the electron density and pressure. Both of these effects highlight the differing impact of active galactic nuclei and supernova feedback on the gas in galaxy groups compared to massive clusters. We verified that we see qualitatively similar features in the SIMBA hydro-dynamical simulations, suggesting these effects could be generic features. Finally, we provide a parametric formula for the electron pressure and density profile as a function of dark matter halo mass, halo concentration, and redshift. These fitting formulae can reproduce the distribution of density and pressure of clusters and will be useful in extracting cosmological information from upcoming CMB surveys.