A study of the hydrostatic mass bias dependence and evolution within The Three Hundred clusters

TL;DR

This study analyzes the hydrostatic mass bias in simulated galaxy clusters, revealing its dependence on cluster dynamics and evolution during mergers, with implications for cosmological measurements.

Contribution

It provides a detailed analysis of the hydrostatic mass bias dependence and evolution in simulated clusters, especially during major mergers, highlighting the impact of dynamical state.

Findings

Bias shows no correlation with redshift, concentration, or mass.

Scatter in bias is larger for disturbed, high-growth, low-concentration clusters.

Bias varies significantly during merger events, affecting mass estimates.

Abstract

We use a set of about 300 simulated clusters from The Three Hundred Project to calculate their hydrostatic masses and evaluate the associated bias by comparing them with the true cluster mass. Over a redshift range from 0.07 to 1.3, we study the dependence of the hydrostatic bias on redshift, concentration, mass growth, dynamical state, mass, and halo shapes. We find almost no correlation between the bias and any of these parameters. However, there is a clear evidence that the scatter of the mass-bias distribution is larger for low-concentrated objects, high mass growth, and more generically for disturbed systems. Moreover, we carefully study the evolution of the bias of twelve clusters throughout a major-merger event. We find that the hydrostatic-mass bias follows a particular evolution track along the merger process: to an initial significant increase of the bias recorded at the begin of merger, a constant plateaus follows until the end of merge, when there is a dramatic decrease in the bias before the cluster finally become relaxed again. This large variation of the bias is in agreement with the large scatter of the hydrostatic bias for dynamical disturbed clusters. These objects should be avoided in cosmological studies because their exact relaxation phase is difficult to predict, hence their mass bias cannot be trivially accounted for.