Probing the evolution of galaxy clusters with the SZ Effect

TL;DR

This paper explores how the thermal Sunyaev-Zel'dovich effect can be used to study the evolution of galaxy clusters by analyzing pressure patterns related to entropy levels in the intracluster medium across different redshifts.

Contribution

It demonstrates how SZ effect patterns relate to ICM entropy and proposes using high-resolution SZ observations to trace cluster evolution up to redshift 2.

Findings

SZ effect patterns correlate with ICM entropy levels.

High-resolution SZ maps can identify low-entropy cores and high-entropy outskirts.

Potential to study cluster evolution modes up to z~2.

Abstract

In galaxy clusters the thermal Sunyaev-Zel'dovich (SZ) effect from the hot intracluster medium (ICM) provides a direct, self-contained measure of the pressure integrated over crossing lines of sight, that is intrinsically independent of redshift and well suited for evolutionary studies. We show in detail how the size of the effect and its pattern on the sky plane are directly related to the entropy levels in the ICM, and how they characterize the cluster cores and outskirts independently. We find that at redshifts z<0.3 the signals to be expected in the cores considerably exceed those detected at 10' resolution with the Planck satellite. We propose that at 1' resolutions as implemented on recent ground instrumentation for mapping features in individual clusters, the average patterns of the SZ signals can provide a direct and effective way to find and count cool, low-entropy cores and hot, high-entropy outskirts out to z~2. Such counts will tell the timing and the mode of the processes that drive the evolution of the ICM from the distant to the local cluster population.