On the ability of spectroscopic SZ effect measurements to determine the temperature structure of galaxy clusters

TL;DR

This paper demonstrates that spatially resolved spectroscopic measurements of the Sunyaev-Zel'dovich effect can accurately determine the temperature profiles of galaxy clusters, offering a complementary or superior alternative to X-ray methods.

Contribution

It develops a formalism and inversion technique for extracting cluster temperature profiles from spectroscopic SZE data, applicable to various cluster types and non-thermal phenomena.

Findings

SZE measurements can match or surpass X-ray temperature accuracy.

Optimal frequency bands for temperature determination are identified.

Method can also characterize non-thermal electron populations.

Abstract

(abridged) We explore in this paper the ability of spatially resolved spectroscopic measurements of the SZ effect (SZE) to determine the temperature profile of galaxy clusters. We derive a general formalism for the thermal SZE in galaxy clusters with a non-uniform temperature profile that can be applied to both cool-core clusters and non-cool core cluster with an isothermal or non-isothermal temperature structure. We derive an inversion technique through which the electron distribution function can be extracted from spectroscopic SZE observations over a wide frequency range. We study the fitting procedure to extract the cluster temperature from a set of simulated spatially resolved spectroscopic SZE observations in different bands of the spectrum, from 100 to 450 GHz. The results of our analysis for three different cluster prototypes (A2199 with a low-temperature cool core, Perseus with a relatively high-temperature cool core, Ophiuchus with an isothermal temperature distribution) provide both the required precision of the SZE observations and the optimal frequency bands for a determination of the cluster temperature similar or better than that obtainable from X-ray observations. The precision of SZE-derived temperature is also discussed for the outer regions of clusters. We also study the possibility to extract, from our method, the parameters characterizing the non-thermal SZE spectrum of the relativistic plasma contained in the lobes of radio galaxies as well as the spectrum of relativistic electrons co-spatially distributed with the thermal plasma in clusters with non-thermal phenomena. We find that the next generation SZE experiments with spectroscopic capabilities can provide precise temperature distribution measurements (...)