Using hydrodynamical simulations, we study how well the underlying gravitational potential of a galaxy cluster can be modelled dynamically with different types of tracers. In order to segregate different systematics and the effects of varying estimator performances, we first focus on applying a generic minimal assumption method (oPDF) to model the simulated haloes using the full 6D phase-space information. We show that the halo mass and concentration can be recovered in an ensemble unbiased way, with a stochastic bias that varies from halo to halo, mostly reflecting deviations from steady state in the tracer distribution. The typical systematic uncertainty is ∼0.17 dex in the virial mass and ∼0.17 dex in the concentration as well when dark matter (DM) particles are used as tracers. The dynamical state of satellite galaxies are close to that of DM particles, while intracluster stars are less in a steady state, resulting in an ∼0.26-dex systematic uncertainty in mass. Compared with galactic haloes hosting Milky-Way-like galaxies, cluster haloes show a larger stochastic bias in the recovered mass profiles. We also test the accuracy of using intracluster gas as a dynamical tracer modelled through a generalized hydrostatic equilibrium equation, and find a comparable systematic uncertainty in the estimated mass to that using DM. Lastly, we demonstrate that our conclusions are largely applicable to other steady-state dynamical models including the spherical Jeans equation, by quantitatively segregating their statistical efficiencies and robustness to systematics. We also estimate the limiting number of tracers that leads to the systematics-dominated regime in each case.

中文翻译：

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对星团光晕的动力学建模有何期待——I. 不同动力学示踪剂的信息内容

使用流体动力学模拟，我们研究了使用不同类型的示踪剂动态模拟星系团潜在引力势的能力。为了区分不同的系统和不同估计器性能的影响，我们首先关注应用通用最小假设方法 (oPDF) 来使用完整的 6D 相空间信息对模拟光晕进行建模。我们表明，晕质量和浓度可以以整体无偏的方式恢复，随机偏差随晕而变化，主要反映示踪剂分布中与稳态的偏差。当使用暗物质 (DM) 粒子作为示踪剂时，典型的系统不确定性在维里质量中约为 0.17 dex，在浓度中约为 0.17 dex。卫星星系的动力学状态接近于 DM 粒子，而星团内恒星不太处于稳定状态，导致质量的系统不确定性约为 0.26-dex。与拥有类似银河系的星系的星系晕相比，星团晕在恢复的质量剖面中显示出更大的随机偏差。我们还测试了使用团内气体作为通过广义静水平衡方程建模的动态示踪剂的准确性，并发现估计质量的系统不确定性与使用 DM 的系统不确定性相当。最后，我们证明了我们的结论在很大程度上适用于其他稳态动力学模型，包括球形牛仔裤方程，通过定量分离它们的统计效率和对系统学的鲁棒性。