A multisimulation study of relativistic SZ temperature scalings in galaxy clusters and groups

The Sunyaev-Zeldovich (SZ) effect is a powerful tool in modern cosmology. With future observations promising ever improving SZ measurements, the relativistic corrections to the SZ signals from galaxy groups and clusters are increasingly relevant. As such, it is important to understand the differences between three temperature measures: (a) the average relativistic SZ (rSZ) temperature, (b) the mass-weighted temperature relevant for the thermal SZ (tSZ) effect, and (c) the X-ray spectroscopic temperature. In this work, we compare these cluster temperatures, as predicted by the BAHAMAS & MACSIS, ILLUSTRISTNG, MAGNETICUM, and THE THREE HUNDRED PROJECT simulations. Despite the wide range of simulation parameters, we find the SZ temperatures are consistent across the simulations. We estimate a similar or equal to 10 per cent level correction from rSZ to clusters with Y similar or equal to 10(-4) Mpc(-2). Our analysis confirms a systematic offset between the three temperature measures; with the rSZ temperature similar or equal to 20 per cent larger than the other measures, and diverging further at higher redshifts. We demonstrate that these measures depart from simple self-similar evolution and explore how they vary with the defined radius of haloes. We investigate how different feedback prescriptions and resolutions affect the observed temperatures, and discover the SZ temperatures are rather insensitive to these details. The agreement between simulations indicates an exciting avenue for observational and theoretical exploration, determining the extent of relativistic SZ corrections. We provide multiple simulation-based fits to the scaling relations for use in future SZ modelling.

Automated summary

The Sunyaev-Zeldovich (SZ) effect is an important tool in cosmology. This study compares cluster temperatures predicted by different simulations and finds consistent SZ temperatures across the simulations. However, there is a systematic offset between the relativistic SZ (rSZ) temperature and other measures, with rSZ temperature being approximately 20% higher. The study also explores the variations of these measures with halo radius and investigates the effects of different feedback prescriptions and resolutions on the observed temperatures.