利用XRISM观测附近星系团内星系际介质的动力学结构
Kinetic structure of the intracluster medium across nearby clusters observed with XRISM
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中文总结 AI 辅助
该研究利用XRISM/Resolve构建星系团ICM气体运动样本，汇总测量数据并比较相关参数，通过分析冷核与非冷核系统差异，区分不同尺度运动，还与预测比较，开始解析ICM投影动力学结构，而非单一湍流序列。
中文摘要 AI 辅助
XRISM/Resolve正在构建一个直接测量星系团内星系际介质（ICM）气体运动的样本，揭示不同的投影动力学状态。我们汇总了19个附近星系团中的45次XRISM/Resolve测量数据，并将它们置于一个共同的、发射加权有效视线尺度$\ell_{\rm eff}$上。我们比较了视线速度弥散$\sigma_v$、整体速度幅度$|v_{\rm bulk}|$、它们的比值$R_v \equiv |v_{\rm bulk}|/\sigma_v$以及非热压力代理。受干扰的非冷核系统并非简单地是松弛冷核区域的高弥散对应物。相反，冷核中心、冷核外部区域和非冷核系统之间的差异主要由相对于未解析线展宽的相干视线运动驱动：$R_v$在冷核区域往往低于1，但在非冷核系统中常常超过1，冷核中心的平均$R_v$从0.45升至非冷核系统中的1.6。这些诊断有助于区分局部中心线展宽（可能与某些冷核中的AGN反馈有关）与与晃动、合并和晕组装相关的更大尺度相干运动。与正向建模的TNG - Cluster预测的比较表明，许多冷核测量值占据预测的非热压力范围的下部，这与松弛系统中的小流体静力学质量校正和受干扰系统中的较大校正一致。因此，XRISM开始解析跨星系团环境的ICM投影动力学结构，而不是追踪单一的湍流增加序列。
英文摘要
XRISM/Resolve is building a sample of galaxy clusters with directly measured ICM gas motions, revealing diverse projected dynamical states. We compile 45 XRISM/Resolve measurements in 19 nearby galaxy clusters and place them on a common, emission-weighted effective line-of-sight scale, $\ell_{\rm eff}$. We compare the line-of-sight velocity dispersion $σ_v$, bulk velocity amplitude $|v_{\rm bulk}|$, their ratio $R_v \equiv |v_{\rm bulk}|/σ_v$, and non-thermal pressure proxies. Disturbed non-cool-core systems are not simply higher-dispersion counterparts of relaxed cool-core regions. Instead, differences among cool-core centers, cool-core outer regions, and non-cool-core systems are driven mainly by coherent line-of-sight motion relative to unresolved line broadening: $R_v$ tends to remain below unity in cool-core regions but often exceeds unity in non-cool-core systems, with the mean $R_v$ rising from 0.45 in cool-core centers to 1.6 in non-cool-core systems. These diagnostics help separate local central line broadening, likely associated with AGN feedback in some cool cores, from larger-scale coherent motions associated with sloshing, mergers, and halo assembly. Comparison with forward-modeled TNG-Cluster predictions suggests that many cool-core measurements occupy the lower part of the predicted non-thermal pressure range, consistent with small hydrostatic-mass corrections in relaxed systems and larger corrections in disturbed ones. XRISM is thus beginning to resolve the projected kinetic structure of the ICM across cluster environments, rather than tracing a single sequence of increasing turbulence.
