星系团气体速度的间接测量：椭圆度和星系团动力学状态的影响
Indirect Measurements of Gas Velocities in Galaxy Clusters: Effects of Ellipticity and Cluster Dynamic State
摘要：
在等待直接的速度测量的气体运动在热的团内介质，我们依靠间接的探针，包括气体扰动的星系团。利用Omega 500宇宙学模拟中不同动力学状态下的$\sim 80$团簇样本，研究了气体密度、$δρ/ρ$、压强、$δP/P$、X射线表面亮度、Sunyaev-Zeldovich（SZ）y参数和气体运动特征马赫数$M_{\rm 1d}$之间的标度关系.在松弛的簇中，考虑晕椭圆度在$r_{500c}$内将$δρ/ρ$或$δP/P$降低高达2倍。我们确认了一个强的线性相关性之间的$δρ/ρ$（或$δP/P$）和$M_{\rm 1d}$在放松集群，与比例系数$η\approx 1$。对于非松弛簇，相关性不太强，并且对于$δρ/ρ$（$δP/P$）具有较大的$η\approx 1.3\pm 0.5$（$1.5\pm0.5$）。$M_{\rm 1d}$与$δρ/ρ$的幂律标度检验表明，对于松弛的簇，它几乎是线性的，而对于非松弛的簇，它更接近于$δρ/ρ\propto M_{\rm 1d}^2$，支持非线性项和压缩模式的作用越来越大。与以前的研究一致，我们观察到$M_{\rm 1d}$与半径的强相关性。对这些相关性进行校正后，松弛（扰动）集群的$M_{\rm 1d}$中剩余分散度为$\sim 4 (7)$ %。流体静力学质量偏差与$M_{\rm 1d}$的相关性与松弛团簇中的$δρ/ρ$一样强。对导出的趋势进行校正后的剩余散射是$\sim 6-7$ %。这些预测可以与现有的X射线和SZ观测的星系团结合即将到来的速度测量与X射线微量热仪进行验证。
英文摘要：
While awaiting direct velocity measurement of gas motions in the hot intracluster medium, we rely on indirect probes, including gas perturbations in galaxy clusters. Using a sample of $\sim 80$ clusters in different dynamic states from Omega500 cosmological simulations, we examine scaling relations between the fluctuation amplitudes of gas density, $δρ/ρ$, pressure, $δP/P$, X-ray surface brightness, Sunyaev-Zeldovich (SZ) y-parameter, and the characteristic Mach number of gas motions, $M_{\rm 1d}$. In relaxed clusters, accounting for halo ellipticities reduces $δρ/ρ$ or $δP/P$ by a factor of up to 2 within $r_{500c}$. We confirm a strong linear correlation between $δρ/ρ$ (or $δP/P$) and $M_{\rm 1d}$ in relaxed clusters, with the proportionality coefficient $η\approx 1$. For unrelaxed clusters, the correlation is less strong and has a larger $η\approx 1.3\pm 0.5$ ($1.5\pm0.5$) for $δρ/ρ$ ($δP/P$). Examination of the power-law scaling of $M_{\rm 1d}$ with $δρ/ρ$ shows that it is almost linear for relaxed clusters, while for the unrelaxed ones, it is closer to $δρ/ρ\propto M_{\rm 1d}^2$, supporting an increasing role of non-linear terms and compressive modes. In agreement with previous studies, we observe a strong correlation of $M_{\rm 1d}$ with radius. Correcting for these correlations leaves a residual scatter in $M_{\rm 1d}$ of $\sim 4 (7)$ per cent for relaxed (perturbed) clusters. Hydrostatic mass bias correlates with $M_{\rm 1d}$ as strongly as with $δρ/ρ$ in relaxed clusters. The residual scatters after correcting for derived trends is $\sim 6-7$ per cent. These predictions can be verified with existing X-ray and SZ observations of galaxy clusters combined with forthcoming velocity measurements with X-ray microcalorimeters.
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