AI 中文总结
本研究利用XRISM的Resolve光谱分析17个星系团，通过Fe-K线诊断检验ICM的CIE框架，发现线比值存在与共振散射、额外原子过程相关的偏差，为探测ICM物理提供新线索。
AI 中文摘要
我们旨在通过主要基于分辨的铁-凯（Fe-K）发射线进行线诊断，来检验星系团内介质（ICM）中碰撞电离平衡（CIE）框架的有效性。方法：我们分析了17个星系团的Resolve全阵列光谱。将显著的Fe-K线成分（Fe XXV的w、x、y、z线，以及Fe XXVI的Lyα1、Lyα2线）从等离子体发射模型中移除，改用高斯轮廓拟合，从而无需依赖合成光谱模型即可直接测量线通量。一些冷核系统的w/z比值比模型预测值低约20%，且w线比z线更宽，这与共振散射效应一致。部分天体的y/x比值与模型预测存在微小偏差，暗示可能存在电子复合引发的级联过程及低电离铁的贡献。Fe Lyα2/Lyα1比值整体接近约0.5的预期值，光子统计良好的样本更倾向于0.55；这一细微过量与磁偶极（M1）跃迁对Lyα2的未分辨贡献相符，而所考虑的某一原子代码未包含该跃迁。更有趣的是，约7 keV的系统优先呈现Lyα2/Lyα1比值高于0.55。尽管这一趋势的统计显著性有限，但它表明分辨的Fe Lyα光谱可能为探测碰撞激发之外的额外原子过程提供灵敏探针，包括双电子复合、辐射复合及极化效应。
英文摘要
We aim to test the validity of the CIE framework in the ICM by performing line diagnostics based mainly on resolved Fe-K emission lines. Methods. We analyse Resolve full-array spectra of 17 galaxy clusters. Prominent Fe-K line components (the Fe xxv w, x, y, z, and Fe xxvi Lyα1,2 lines) are removed from plasma emission models and instead fitted with Gaussian profiles, enabling direct measurements of line fluxes without relying on synthetic spectral models. Some cool-core systems show w/z ratios lower than predicted by about 20 per cent, and a broader w than z, consistent with resonant scattering effects. The y/x ratios exhibit marginal deviations from model predictions for some objects, suggesting possible origins of cascade process due to electron recombination and contribution from low-ionised Fe. The Fe Lyα2/Lyα1 ratios are globally close to the expected value of about 0.5, and the samples with good photon statistics prefer 0.55. This subtle excess is consistent with an unresolved contribution to Lyα2 from the magnetic-dipole (M1) transition, which is absent from one of the atomic codes considered here. More interestingly, systems at around 7 keV preferentially exhibit Lyα2/Lyα1 ratios above 0.55. Although the statistical significance of this trend is limited, it suggests that resolved Fe Lyα spectroscopy may provide a sensitive probe of additional atomic processes to collisional excitation, including dielectronic and radiative recombination and polarisation effects.
Comments10 pages, 5 figures, 3 tables. submitted to A&A
