X-ray spectra of galaxy clusters are dominated by the thermal emission from the hot intracluster medium. In some cases, besides the thermal component, spectral models require additional components associated, e.g., with resonant scattering and charge exchange. The latter produces mostly underluminous fine spectral features. Detection of the extra components therefore requires high spectral resolution. The upcoming X-ray missions will provide such high resolution, and will allow spectroscopic diagnostics of clusters beyond the current simple thermal modeling. A representative science case is resonant scattering, which produces spectral distortions of the emission lines from the dominant thermal component. Accounting for the resonant scattering is essential for accurate abundance and gas motion measurements of the ICM. The high resolution spectroscopy might also reveal/corroborate a number of new spectral components, including the excitation by non-thermal electrons, the deviation from ionization equilibrium, and charge exchange from surface of cold gas clouds in clusters. Apart from detecting new features, future high resolution spectroscopy will also enable a much better measurement of the thermal component. Accurate atomic database and appropriate modeling of the thermal spectrum are therefore needed for interpreting the data.

中文翻译：

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星系团的 X 射线光谱：超越 CIE 建模

星系团的 X 射线光谱主要由来自热星系团内介质的热辐射决定。在某些情况下，除了热成分之外，光谱模型还需要额外的成分，例如与共振散射和电荷交换相关的成分。后者主要产生亮度不足的精细光谱特征。因此，额外成分的检测需要高光谱分辨率。即将到来的 X 射线任务将提供如此高的分辨率，并将允许在当前简单的热建模之外对星团进行光谱诊断。一个代表性的科学案例是共振散射，它会产生来自主要热成分的发射线的光谱失真。考虑共振散射对于 ICM 的准确丰度和气体运动测量至关重要。高分辨率光谱还可能揭示/证实许多新的光谱成分，包括非热电子的激发、电离平衡的偏离以及来自簇中冷气体云表面的电荷交换。除了检测新特征外，未来的高分辨率光谱还将能够更好地测量热成分。因此，需要准确的原子数据库和热谱的适当建模来解释数据。未来的高分辨率光谱也将能够更好地测量热成分。因此，需要准确的原子数据库和热谱的适当建模来解释数据。未来的高分辨率光谱也将能够更好地测量热成分。因此，需要准确的原子数据库和热谱的适当建模来解释数据。