AI 中文总结
本研究利用 Planck 巡天观测数据重新分析 Coma 星系团的 SZ 面亮度涨落，通过基于归一化流的模拟推断框架约束 ICM 湍流性质，结果与 XRISM 测量一致，为多探针研究提供方法基础。
AI 中文摘要
星系团内介质（ICM）中的湍流会影响星系团的热力学过程与位力化过程，促成非热压支撑并影响流体静力学质量估计。由于密度、压强等可观测量与 underlying 速度场之间存在非线性关系，通过热力学涨落表征这种湍流在观测上仍具挑战性。本研究旨在通过基于 Planck 巡天对 Coma 星系团的观测数据，对 Sunyaev-Zel'dovich（SZ）面亮度涨落进行全面重新分析，从而约束 ICM 湍流的性质。我们分析了 SZ 涨落的二维功率谱，假设湍流为 Kolmogorov 型，对 underlying 的三维压强涨落功率谱进行建模。我们借助基于模拟的推断框架（该框架依赖归一化流以准确恢复后验分布）推断关键参数。通过约束压强涨落功率谱，我们得以推断 Coma 星系团中湍流的性质，发现注入尺度较大，为 $l_{\text{inj}} = 540^{+450}_{-200}$ kpc，斜率为 $α= 3.50_{-0.46}^{+0.50}$（在高斯先验下），三维马赫数较大，为 $\text{M}_{3D} = 0.60^{+0.13}_{-0.09}$。这些值对应的湍流速度范围为 $σ_{v,\text{ }3D} = 357-1095$ km/s，非热压占比为 $P_{\text{turb}}/P_{\text{tot}} = 0.17_{-0.04}^{+0.06}$。我们的结果与近期 XRISM 的直接速度测量结果一致，支持 Coma 星系团中存在显著湍流的图景，凸显了其 ICM 内部动力学过程的复杂相互作用。我们应用于 SZ 涨落的基于模拟的推断方法，为结合 SZ 与 X 射线数据以及直接与间接观测的系统性多探针研究铺平了道路。
英文摘要
Turbulence within the intracluster medium (ICM) influences galaxy cluster thermodynamics and virialisation, contributing to non-thermal pressure support and impacting hydrostatic mass estimates. Characterising this turbulence through thermodynamic fluctuations remains observationally challenging due to the non-linear relationships between observables such as density and pressure, and the underlying velocity field. This study aims to constrain the properties of ICM turbulence by performing a comprehensive reanalysis of the Sunyaev-Zel'dovich (SZ) surface brightness fluctuations based on Planck survey observations of the Coma cluster. We analyse the 2D power spectrum of SZ fluctuations, modelling the underlying 3D pressure fluctuation power spectrum assuming Kolmogorov-type turbulence. We infer key parameters from a simulation-based inference framework relying on normalizing flows to accurately recover posterior distributions. By constraining the pressure fluctuation power spectrum, we are able to infer the properties of turbulence in the Coma cluster, finding a large injection scale of $l_{\text{inj}} = 540^{+450}_{-200}$ kpc, a slope of $α= 3.50_{-0.46}^{+0.50}$ (under Gaussian prior), and a substantial 3D Mach number of $\mathcal{M}_{3D} = 0.60^{+0.13}_{-0.09}$. These values correspond to turbulent velocities in the range $σ_{v,\text{ }3D} = 357-1095$ km/s and a non thermal pressure fraction of $P_{\text{turb}}/P_{\text{tot}} = 0.17_{-0.04}^{+0.06}$. Our results are consistent with recent direct velocity measurements from XRISM, supporting a scenario of significant turbulence in the Coma cluster and highlighting the complex interplay of dynamical processes within its ICM. Our simulation-based inference approach applied to SZ fluctuations paves the way for systematic multi-probe studies combining SZ and X-ray data, as well as direct and indirect observations.
Comments12 pages, accepted for publication in A&A
