James Webb Space Telescope observations have spectroscopically confirmed the existence of galaxies as early as 300 Myr after the Big Bang and with a higher number density than what was expected based on galaxy formation models and Hubble Space Telescope observations. Yet, most sources confirmed spectroscopically so far in the first 500 Myr have rest-frame ultraviolet (UV) luminosities below the characteristic luminosity (\({M}_\mathrm{UV}^{* }\)), limiting the signal-to-noise ratio for investigating substructure. Here we present a high-resolution spectroscopic and spatially resolved study of a bright galaxy (M_UV = −21.66 ± 0.03, \(\sim 2{M}_\mathrm{UV}^{* }\)) at a redshift z = 9.3127 ± 0.0002 (510 Myr after the Big Bang) with an estimated stellar mass of \(\left(1.6_{-0.4}^{+0.5}\right)\times 10^{9}\,M_{\odot }\), forming \(1{9}_{-6}^{+5}\) solar masses per year and with a metallicity of about one tenth that of solar. The system has a morphology typically associated with two interacting galaxies, with a two-component main clump of very young stars (age less than 10 Myr) surrounded by an extended stellar population (120 ± 20 Myr old, identified from modelling the NIRSpec spectrum) and an elongated clumpy tidal tail. The observations acquired at high spectral resolution identify oxygen, neon and hydrogen emission lines, as well as the Lyman break, where there is evidence of substantial absorption of Lyα. The [O ii] doublet is resolved spectrally, enabling an estimate of the electron number density and ionization parameter of the interstellar medium and showing higher densities and ionization than in analogues at lower redshifts. We identify evidence of absorption lines (silicon, carbon and iron), with low confidence individual detections but a signal-to-noise ratio larger than 6 when stacked. These absorption features suggest that Lyα is damped by the interstellar and circumgalactic media. Our observations provide evidence of a rapid and efficient build-up of mass and metals in the immediate aftermath of the Big Bang through mergers, demonstrating that there were massive galaxies with several billion stars at early times.

詹姆斯·韦伯太空望远镜的观测已经通过光谱证实了早在大爆炸后 300 迈尔的星系的存在，并且其数量密度比基于星系形成模型和哈勃太空望远镜观测的预期更高。然而，迄今为止通过光谱证实的大多数来源在前 500 Myr 中的静止帧紫外 (UV) 光度低于特征光度 ( \({M}_\mathrm{UV}^{* }\) )，限制了信号 -用于研究子结构的信噪比。在这里，我们提出了对红移z处的明亮星系 ( M _UV  = −21.66 ± 0.03, \(\sim 2{M}_\mathrm{UV}^{* }\) )的高分辨率光谱和空间分辨研究 = 9.3127 ± 0.0002（大爆炸后 510 Myr），估计恒星质量为\(\left(1.6_{-0.4}^{+0.5}\right)\times 10^{9}\,M_{\odot }\) ，每年形成\(1{9}_{-6}^{+5}\) 个太阳质量，金属丰度约为太阳的十分之一。该系统的形态通常与两个相互作用的星系相关，其中有一个由非常年轻的恒星（年龄小于 10 Myr）组成的两部分主团块，周围环绕着扩展的恒星群（年龄为 120 ± 20 Myr，通过 NIRSpec 光谱建模确定）和一条细长的块状潮汐尾。在高光谱分辨率下获得的观测结果确定了氧、氖和氢的发射线，以及莱曼断裂线，其中有证据表明 Lyα 有大量吸收。[O ii ]双峰通过光谱解析，能够估计星际介质的电子数密度和电离参数，并在较低红移下显示出比类似物更高的密度和电离。我们确定了吸收线（硅、碳和铁）的证据，个体检测的置信度较低，但堆叠时信噪比大于 6。这些吸收特征表明 Lyα 受到星际和银河系介质的阻尼。我们的观测提供了证据，证明大爆炸后质量和金属通过合并迅速而有效地积累，证明早期存在着拥有数十亿颗恒星的巨大星系。