Total mass biases in X-ray galaxy clusters

TL;DR

This study assesses the accuracy of X-ray derived galaxy cluster masses by analyzing biases from observational assumptions and physical effects using simulated clusters.

Contribution

It provides a comprehensive evaluation of biases affecting X-ray mass estimates through simulations, considering modeling, extrapolation, and dynamical state effects.

Findings

X-ray mass estimates are biased by modeling and extrapolation assumptions.

Dynamically disturbed clusters show larger mass biases.

Different temperature definitions impact the accuracy of hydrostatic mass estimates.

Abstract

The exploitation of clusters of galaxies as cosmological probes relies on accurate measurements of their total gravitating mass. X-ray observations provide a powerful means of probing the total mass distribution in galaxy clusters, but might be affected by observational biases and rely on simplistic assumptions originating from our limited understanding of the intracluster medium physics. This paper is aimed at elucidating the reliability of X-ray total mass estimates in clusters of galaxies by properly disentangling various biases of both observational and physical origin. We use N-body/SPH simulation of a large sample of ~100 galaxy clusters and investigate total mass biases by comparing the mass reconstructed adopting an observational-like approach with the true mass in the simulations. X-ray surface brightness and temperature profiles extracted from the simulations are fitted with different models and adopting different radial fitting ranges in order to investigate modeling and extrapolation biases. Different theoretical definitions of gas temperature are used to investigate the effect of spectroscopic temperatures and a power ratio analysis of the surface brightness maps allows us to assess the dependence of the mass bias on cluster dynamical state. Moreover, we perform a study on the reliability of hydrostatic and hydrodynamical equilibrium mass estimates using the full three-dimensional information in the simulation.[abridged]