An analysis of the temperature structure of galaxy clusters by means of the thermal Sunyaev-Zel'dovich effect

TL;DR

This paper proposes a method to measure the temperature structure of merging galaxy clusters using the Sunyaev-Zel'dovich effect, specifically through intensity ratios at different frequencies, which can reveal shock wave features.

Contribution

It introduces a novel approach utilizing SZ intensity ratios at specific frequencies to accurately determine gas temperature in merging clusters, accounting for relativistic effects.

Findings

SZ intensity ratio at 128 GHz and 369 GHz reveals temperature features.

Relativistic corrections improve the accuracy of SZ-based temperature measurements.

Method effectively identifies shock wave structures in simulated merging clusters.

Abstract

Measurements of the Sunyaev-Zel'dovich (hereafter SZ) effect distortion of the cosmic microwave background provide us with an independent method to derive the gas temperature of galaxy clusters. In merging galaxy clusters the gas distribution is inhomogeneous and, therefore, the method of temperature measuring based on the SZ effect should be more relevant than that based on an X-ray emission analysis. Here we study a method for measuring the gas temperature in merging clusters by means of the SZ effect. Our calculations of intensity maps of the SZ effect include relativistic corrections considered within the framework of the Wright formalism and utilize a cosmological numerical simulation of a merging galaxy cluster evolved with its baryon physics. We found that the gas temperature in merging clusters can be measured by means of the ratio of the SZ intensity at a low frequency (128 GHz) to that at a high frequency (369 GHz). This SZ intensity ratio permits us to reveal prominent features of the temperature structure caused by violent merger shock waves. Therefore, measurements of the ratio of the SZ intensities are a promising tool for measuring gas temperature in merging galaxy clusters.