The Beta-Model Problem: The Incompatibility of X-ray and Sunyaev-Zeldovich Effect Model Fitting for Galaxy Clusters

TL;DR

This study reveals fundamental incompatibilities between X-ray and Sunyaev-Zeldovich effect model fittings for galaxy clusters, leading to biased estimates, and proposes a correction using a non-isothermal beta-model with a universal temperature profile.

Contribution

It demonstrates the incompatibility between X-ray and SZE model fits and introduces a correction method using a non-isothermal beta-model with a universal temperature profile.

Findings

X-ray fitted beta-model parameters cause biases in SZE-based estimates.

A simple correction with a non-isothermal beta-model improves accuracy.

The correction aligns estimated quantities closer to true values.

Abstract

We have analyzed a large sample of numerically simulated clusters to demonstrate the adverse effects resulting from use of X-ray fitted beta-model parameters with Sunyaev-Zeldovich effect (SZE) data. There is a fundamental incompatibility between model fits to X-ray surface brightness profiles and those done with SZE profiles. Since observational SZE radial profiles are in short supply, the X-ray parameters are often used in SZE analysis. We show that this leads to biased estimates of the integrated Compton y-parameter inside r_{500} calculated from clusters. We suggest a simple correction of the method, using a non-isothermal beta-model modified by a universal temperature profile, which brings these calculated quantities into closer agreement with the true values.