AI 中文总结
本研究对红移z=7.31的大质量恒星形成星系REBELS-25开展多波段高分辨率观测，揭示其形态、ISM条件与运动学，证实该星系当时已存在尘埃丰富、化学富集且动力学冷的星际介质。
AI 中文摘要
我们对红移z=7.31处的大质量恒星形成星系REBELS-25开展了空间分辨的多波段研究，将新的高分辨率ALMA [O III]88μm观测与分辨率匹配的[C II]、尘埃连续谱以及JWST/NIRSpec积分场单元光谱学结合，在约1千秒差距（kpc）的尺度上呈现了再电离时期已知最成熟星系之一的形态、星际介质（ISM）条件及多示踪剂气体运动学。我们发现从静止帧紫外（UV）到远红外（FIR）发射呈现不同形态：UV和光学发射呈团块状且不规则，而FIR发射可由近指数盘剖面很好描述，[C II]的延伸范围最大。对比分辨后的UV与FIR发射，我们发现星系中被遮挡的恒星形成贡献了总恒星形成率的约55%-98%，表明尘埃消光强烈塑造了观测到的UV和光学形态。分辨后的电离线诊断在~1 kpc分辨率下未显示源内显著变化，与已识别区域间ISM条件大致相似一致。运动学建模显示，由[O III]88μm示踪的暖电离气体和由[C II]示踪的冷中性气体共享同一大尺度旋转结构，且均为动力学冷态，有序运动与随机运动的比值V/σ分别约为11和4.5，尽管我们发现了无法用简单旋转盘很好描述的非圆运动证据。总体而言，这些结果进一步支持了REBELS-25在z=7.31时已存在尘埃丰富、化学富集且动力学冷的ISM的图景。
英文摘要
We present a spatially resolved, multi-wavelength study of the massive, star-forming galaxy REBELS-25 at a redshift of $z=7.31$. We combine new high-resolution ALMA [O III]88$μ$m observations with resolution-matched [C II], dust continuum, and JWST/NIRSpec IFU spectroscopy, providing a $\lesssim1$ kpc view of the morphology, interstellar medium (ISM) conditions, and multi-tracer gas kinematics of one of the most mature galaxies known in the reionisation era. We find differing morphologies from the rest-frame UV to far-infrared (FIR) emission, with the UV and optical emission appearing clumpy and irregular, whereas the FIR emission is well-described by near-exponential disc profiles, with [C II] being the most extended. Comparing the resolved UV and FIR emission, we find that obscured star formation contributes $\sim55$-$98$% of the total star formation rate across the galaxy, demonstrating that dust obscuration strongly shapes the observed UV and optical morphology. Resolved ionisation-line diagnostics show no significant variation across the source at $\sim1$ kpc resolution, consistent with broadly similar ISM conditions among the identified regions. Kinematic modelling reveals that both the warm ionised gas, traced by [O III]88$μ$m, and the colder neutral gas, traced by [C II], share the same large-scale rotating structure and are dynamically cold, with ratios of ordered-to-random motion, $V/σ$, of $\sim11$ and 4.5, respectively, although we find evidence for non-circular motions that are not well-described by a simple rotating disc. Overall, these results further support a picture in which REBELS-25 hosts a dusty, chemically enriched, and dynamically cold ISM already in place at $z=7.31$.
Comments28 pages, 11 figures. Submitted to MNRAS
