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The majority of massive disk galaxies in the local Universe show a stellar barred structure in their central regions, including our Milky Way 1,2 . Bars are supposed to develop in dynamically cold stellar disks at low redshift, as the strong gas turbulence typical of disk galaxies at high redshift suppresses or delays bar formation 3,4 . Moreover, simulations predict bars to be almost absent beyond z = 1.5 in the progenitors of Milky Way-like galaxies 5,6 . Here we report observations of ceers-2112, a barred spiral galaxy at redshift z phot  ≈ 3, which was already mature when the Universe was only 2 Gyr old. The stellar mass (M ★  = 3.9 × 10 9  M ⊙ ) and barred morphology mean that ceers-2112 can be considered a progenitor of the Milky Way 7-9 , in terms of both structure and mass-assembly history in the first 2 Gyr of the Universe, and was the closest in mass in the first 4 Gyr. We infer that baryons in galaxies could have already dominated over dark matter at z ≈ 3, that high-redshift bars could form in approximately 400 Myr and that dynamically cold stellar disks could have been in place by redshift z = 4-5 (more than 12 Gyrs ago) 10,11 ., (© 2023. The Author(s).)

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 1-3 . Observations with the James Webb Space Telescope (JWST) have uncovered a surprisingly high abundance of candidates for early star-forming galaxies, with distances (redshifts, z), estimated from multiband photometry, as large as z ≈ 16, far beyond pre-JWST limits 4-9 . Although such photometric redshifts are generally robust, they can suffer from degeneracies and occasionally catastrophic errors. Spectroscopic measurements are required to validate these sources and to reliably quantify physical properties that can constrain galaxy formation models and cosmology 10 . Here we present JWST spectroscopy that confirms redshifts for two very luminous galaxies with z > 11, and 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 colours 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 deviations from physical properties (such as the stellar initial mass function) that are generally believed to hold at later times., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.