Clusters of galaxies are useful tools to constrain cosmological parameters, only if their masses can be correctly inferred from observations. In particular, X-ray and Sunyaev–Zeldovich (SZ) effect observations can be used to derive masses within the framework of the hydrostatic equilibrium. Therefore, it is crucial to have a good control of the possible mass biases that can be introduced when this hypothesis is not valid. In this work, we analysed a set of 260 synthetic clusters from the MUSIC simulation project at redshifts 0 ≤ z ≤ 0.82. We estimate the hydrostatic mass of the MUSIC clusters from X-ray only (temperature and density) and from X-ray and SZ (density and pressure). Then, we compare them with the true 3D dynamical mass. The biases are of the order of 20 per cent. We find that using the temperature instead of the pressure leads to a smaller bias, although the two values are compatible within 1σ. Non-thermal contributions to the total pressure support, arising from bulk motion and turbulence of the gas, are also computed and show that they are sufficient to account for this bias. We also present a study of the correlation between the mass bias and the dynamical state of the clusters. A clear correlation is shown between the relaxation state of the clusters and the bias factor. We applied the same analysis on a subsample of 32 objects, already selected for supporting the NIKA2 SZ Large Program.

中文翻译：

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探索 MUSIC 集群中的静水质量偏差：应用于 NIKA2 模拟样本

星系团是约束宇宙学参数的有用工具，前提是它们的质量可以从观测中正确推断出来。特别是，X 射线和 Sunyaev-Zeldovich (SZ) 效应观测可用于推导流体静力平衡框架内的质量。因此，当这个假设不成立时，对可能引入的质量偏差进行良好控制至关重要。在这项工作中，我们分析了 MUSIC 模拟项目中红移 0 ≤ z ≤ 0.82 的一组 260 个合成集群。我们仅从 X 射线（温度和密度）以及从 X 射线和 SZ（密度和压力）估计 MUSIC 星团的静水质量。然后，我们将它们与真正的 3D 动态质量进行比较。偏差约为 20%。我们发现使用温度而不是压力会导致较小的偏差，尽管这两个值在 1σ 内是兼容的。还计算了由气体的整体运动和湍流引起的对总压力支持的非热贡献，并表明它们足以解释这种偏差。我们还研究了质量偏差与集群动态状态之间的相关性。簇的弛豫状态与偏差因子之间显示出明显的相关性。我们对 32 个对象的子样本应用了相同的分析，这些对象已被选为支持 NIKA2 SZ 大型计划。也计算并表明它们足以解释这种偏差。我们还研究了质量偏差与集群动态状态之间的相关性。簇的弛豫状态与偏差因子之间显示出明显的相关性。我们对 32 个对象的子样本应用了相同的分析，这些对象已被选为支持 NIKA2 SZ 大型计划。也计算并表明它们足以解释这种偏差。我们还研究了质量偏差与集群动态状态之间的相关性。簇的弛豫状态与偏差因子之间显示出明显的相关性。我们对 32 个对象的子样本应用了相同的分析，这些对象已被选为支持 NIKA2 SZ 大型计划。