AI 中文总结
本研究依托THESAN-ZOOM模拟，提出基于功率谱的星系成团性量化方法，发现高红移星系成团性与恒星反馈处理及爆发式恒星形成周期相关，可作为早期宇宙爆发式恒星形成的互补探测手段。
AI 中文摘要
近期詹姆斯·韦布空间望远镜（JWST）的观测揭示了多样的高红移星系形态，其中包含一类具有不规则、成团结构的星系群体。这些结构的物理起源，以及观测偏差在多大程度上影响其外观，仍不确定。我们提出一种基于功率谱的方法，用于量化不同空间尺度上的星系成团性，该方法采用辐射流体动力学模拟套件THESAN-ZOOM，其使用了能解析多相星际介质（ISM）的最先进星系形成模型。尽管THESAN-ZOOM星系中的总恒星质量分布通常是平滑的，但在氢α（Hα）、远紫外（FUV）和光学光分布中会出现成团结构。对更短时间尺度恒星形成敏感的示踪剂表现出更明显的小尺度结构（约10²至10³秒差距）。对应的投影光谱遵循P(k)∝k⁻¹至k⁻²的规律，对近期恒星形成更敏感的示踪剂的斜率逐渐变浅，这反映出年轻恒星群体的小尺度功率增强，且空间间歇性更强。该行为与高度可压缩、以激波为主的ISM一致，其中恒星反馈和外流将致密气体重组为丝状和团块状结构。我们还发现，星系成团性取决于恒星反馈的处理方式：较弱的早期恒星反馈会增强质量和光分布中的小尺度功率；成团性在爆发式恒星形成周期中变化显著，这意味着观测样本可能偏向于处于恒星形成增强阶段的星系。因此，星系成团性可作为早期宇宙中爆发式恒星形成的互补探测手段。
英文摘要
Recent JWST observations have revealed diverse high-redshift galaxy morphologies, including a population with irregular and clumpy structures. The physical origin of these structures, and the extent to which observational biases shape their appearance, remain uncertain. We present a power-spectrum-based method for quantifying galaxy clumpiness across spatial scales, using the radiation-hydrodynamic simulation suite THESAN-ZOOM, which employs a state-of-the-art galaxy formation model that resolves the multiphase interstellar medium (ISM). Although the total stellar mass distributions in THESAN-ZOOM galaxies are usually smooth, clumpy structures appear in the H$α$, far-ultraviolet (FUV), and optical light distributions. Tracers sensitive to shorter-timescale star formation exhibit more pronounced small-scale structure ($\sim10^{2}$--$10^{3}{\rm pc}$). The corresponding projected light spectra follow $P(k)\propto k^{-1}$ to $k^{-2}$, with progressively shallower slopes for tracers sensitive to more recent star formation, reflecting enhanced small-scale power and greater spatial intermittency in young stellar populations. This behaviour is consistent with a highly compressible, shock-dominated ISM in which stellar feedback and outflows reorganise dense gas into filamentary and clumpy structures. We also find that galaxy clumpiness depends on the treatment of stellar feedback. Weaker early stellar feedback enhances small-scale power in both the mass and light distributions. Clumpiness also varies strongly over the bursty star formation cycle, implying that observed samples may be biased towards galaxies caught in phases of elevated star formation. Galaxy clumpiness, therefore, could provide a complementary probe of the bursty star formation in the early Universe.
Comments15 pages, 9 figures. Submitted to MNRAS. Comments are welcome!
