Scuola Normale Superiore, Pisa, Italy.
Steward Observatory, University of Arizona, Tucson, AZ, USA.
Nature. 2024 Sep;633(8029):318-322. doi: 10.1038/s41586-024-07860-9. Epub 2024 Jul 29.
The first observations of the James Webb Space Telescope (JWST) have revolutionized our understanding of the Universe by identifying galaxies at redshift z ≈ 13 (refs. ). In addition, the discovery of many luminous galaxies at Cosmic Dawn (z > 10) has suggested that galaxies developed rapidly, in apparent tension with many standard models. However, most of these galaxies lack spectroscopic confirmation, so their distances and properties are uncertain. Here we present JWST Advanced Deep Extragalactic Survey-Near-Infrared Spectrograph spectroscopic confirmation of two luminous galaxies at and z = 13.90 ± 0.17. The spectra reveal ultraviolet continua with prominent Lyman-α breaks but no detected emission lines. This discovery proves that luminous galaxies were already in place 300 million years after the Big Bang and are more common than what was expected before JWST. The most distant of the two galaxies is unexpectedly luminous and is spatially resolved with a radius of 260 parsecs. Considering also the very steep ultraviolet slope of the second galaxy, we conclude that both are dominated by stellar continuum emission, showing that the excess of luminous galaxies in the early Universe cannot be entirely explained by accretion onto black holes. Galaxy formation models will need to address the existence of such large and luminous galaxies so early in cosmic history.
詹姆斯·韦伯太空望远镜（JWST）的首批观测结果通过识别红移 z ≈ 13 的星系，彻底改变了我们对宇宙的理解（参考文献）。此外，宇宙黎明（z > 10）时期许多发光星系的发现表明，星系的发展非常迅速，这与许多标准模型明显存在冲突。然而，这些星系中的大多数缺乏光谱确认，因此其距离和性质存在不确定性。在这里，我们展示了 JWST 高级深外星系近红外光谱仪对两个位于 和 z = 13.90 ± 0.17 的发光星系的光谱确认。光谱显示出紫外线连续体，具有明显的 Lyman-α 断裂，但没有检测到发射线。这一发现证明，在大爆炸后 3 亿年，就已经存在了光度很高的星系，这比 JWST 之前预期的更为普遍。这两个星系中距离最远的一个出人意料地明亮，并且可以通过半径为 260 秒差距的空间分辨率来分辨。考虑到第二个星系的紫外线斜率也非常陡峭，我们得出结论，两者都主要由恒星连续谱发射主导，这表明在早期宇宙中，光度过高的星系不能完全用黑洞吸积来解释。星系形成模型将需要解决在宇宙历史如此早期就存在如此大而明亮的星系的问题。
