近日，美国国家光学-红外天文学研究实验室的Pablo Arrabal Haro及其研究小组取得一项新进展。经过不懈努力，他们证实了早期宇宙中存在非常明亮的星系，并反驳了有关这些星系的一些早期说法。。相关研究成果已于2023年8月14日在国际权威学术期刊《自然》上发表。
该研究团队利用JWST获得了光谱数据，证实了两个非常明亮的星系的红移值超过z=11，同时也发现另一个被认为距离非常遥远的候选星系的实际建议值为z≈16，而不是先前估计的z=4.9。这个候选星系展现出不同寻常的星云线发射和尘埃变红的组合，从而模仿了更遥远物体的颜色。这些发现进一步支持了早期快速形成非常明亮星系的证据，并强调了进行光谱验证的必要性。此外，大量明亮的早期星系的发现，可能揭示了当前星系形成模型中的缺陷，或者与通常认为在后期具有的物理性质（如恒星初始质量函数）存在偏离。
据悉，在宇宙历史的最初5亿年里，第一批恒星和星系形成，为宇宙播下了重元素的种子，并最终使星系间的介质重新电离。通过JWST的观测，令人惊讶地发现了大量早期恒星形成星系的候选者，其距离（红移，z）通过多波段光度法估计，高达z≈16，远远超出了JWST之前的极限。尽管这种方法通常是可靠的，但光度红移可能会受到简并和偶然灾难性误差的影响。因此，需要进行光谱测量来验证这些源，并可靠地量化可以约束星系形成模型和宇宙学的物理特性。
附：英文原文
Title: Confirmation and refutation of very luminous galaxies in the early universe
Author: Haro, Pablo Arrabal, Dickinson, Mark, Finkelstein, Steven L., Kartaltepe, Jeyhan S., Donnan, Callum T., Burgarella, Denis, Carnall, Adam C., Cullen, Fergus, Dunlop, James S., Fernndez, Vital, Fujimoto, Seiji, Jung, Intae, Krips, Melanie, Larson, Rebecca L., Papovich, Casey, Prez-Gonzlez, Pablo G., Amorn, Ricardo O., Bagley, Micaela B., Buat, Vronique, Casey, Caitlin M., Chworowsky, Katherine, Cohen, Seth H., Ferguson, Henry C., Giavalisco, Mauro, Huertas-Company, Marc, Hutchison, Taylor A., Kocevski, Dale D., Koekemoer, Anton M., Lucas, Ray A., McLeod, Derek J., McLure, Ross J., Pirzkal, Norbert, Seill, Lise-Marie, Trump, Jonathan R., Weiner, Benjamin J., Wilkins, Stephen M., Zavala, Jorge A.
Issue&Volume: 2023-08-14
Abstract: During the first 500 million years of cosmic history, the first stars and galaxies formed, seeding the Universe with heavy elements and eventually reionizing the intergalactic medium. Observations with JWST have uncovered a surprisingly high abundance of candidates for early star-forming galaxies, with distances (redshifts, z), estimated from multi-band photometry, as large as z≈16, far beyond pre-JWST limits. While generally robust, such photometric redshifts can suffer from degeneracies and occasionally catastrophic errors. Spectroscopic measurement is required to validate these sources and to reliably quantify physical properties that can constrain galaxy formation models and cosmology. Here we present JWST spectroscopy that confirms redshifts for two very luminous galaxies with z>11, but also demonstrates that another candidate with suggested z≈16 instead has z=4.9, with an unusual combination of nebular line emission and dust reddening that mimics the colors expected for much more distant objects. These results reinforce evidence for the early, rapid formation of remarkably luminous galaxies, while also highlighting the necessity of spectroscopic verification. The large abundance of bright, early galaxies may indicate shortcomings in current galaxy formation models, or deviation from physical properties (such as the stellar initial mass function) that are generally believed to hold at later times.
DOI: 10.1038/s41586-023-06521-7
Source: https://www.nature.com/articles/s41586-023-06521-7
来源：科学网 小柯机器人