Relativistic SZ temperature scaling relations of groups and clusters derived from the BAHAMAS and MACSIS simulations

TL;DR

This paper uses large-scale simulations to analyze relativistic SZ temperature scaling relations in galaxy clusters, revealing significant underestimations in non-relativistic models and providing new correction formulas for improved cosmological measurements.

Contribution

It introduces new relativistic SZ temperature scaling relations derived from simulations, accounting for mass and redshift evolution, and offers practical correction formulas for observational studies.

Findings

Relativistic SZ temperature can be underestimated by 10-40% using standard X-ray relations.

The correction to SZ temperature shows significant dependence on cluster mass and redshift.

New scaling relations and profiles for relativistic SZ temperature are provided for future research.

Abstract

The Sunyaev-Zeldovich (SZ) effect has long been recognized as a powerful cosmological probe. Using the BAHAMAS and MACSIS simulations to obtain $>10,000$ simulated galaxy groups and clusters, we compute three temperature measures and quantify the differences between them. The first measure is related to the X-ray emission of the cluster, while the second describes the non-relativistic thermal SZ (tSZ) effect. The third measure determines the lowest order relativistic correction to the tSZ signal, which is seeing increased observational relevance. Our procedure allows us to accurately model the relativistic SZ (rSZ) contribution and we show that a $\gtrsim 10\%-40\%$ underestimation of this rSZ cluster temperature is expected when applying standard X-ray relations. The correction also exhibits significant mass and redshift evolution, as we demonstrate here. We present the mass dependence of each temperature measure alongside their profiles and a short analysis of the temperature dispersion as derived from the aforementioned simulations. We also discuss a new relation connecting the temperature and Compton-$y$ parameter, which can be directly used for rSZ modelling. Simple fits to the obtained scaling relations and profiles are provided. These should be useful for future studies of the rSZ effect and its relevance to cluster cosmology.