A core in a star-forming disc as evidence of inside-out growth in the early Universe

Baker, William M., Tacchella, Sandro, Johnson, Benjamin D., Nelson, Erica, Suess, Katherine A., D’Eugenio, Francesco, Curti, Mirko, de Graaff, Anna, Ji, Zhiyuan, Maiolino, Roberto, Robertson, Brant, Scholtz, Jan, Alberts, Stacey, Arribas, Santiago, Boyett, Kristan, Bunker, Andrew J., Carniani, Stefano, Charlot, Stephane, Chen, Zuyi, Chevallard, Jacopo, Curtis-Lake, Emma, Danhaive, A. Lola, DeCoursey, Christa, Egami, Eiichi, Eisenstein, Daniel J., Endsley, Ryan, Hausen, Ryan, Helton, Jakob M., Kumari, Nimisha, Looser, Tobias J., Maseda, Michael V., Puskás, Dávid, Rieke, Marcia, Sandles, Lester, Sun, Fengwu, Übler, Hannah, Williams, Christina C., Willmer, Christopher N. A. and Witstok, Joris (2024) A core in a star-forming disc as evidence of inside-out growth in the early Universe. Nature Astronomy. ISSN 2397-3366

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The physical processes that establish the morphological evolution and the structural diversity of galaxies are key unknowns in extragalactic astrophysics. Here we report the finding of the morphologically mature galaxy JADES-GS+53.18343−27.79097, which existed within the first 700 million years of the Universe’s history. This star-forming galaxy with a stellar mass of 400 million solar masses consists of three components: a highly compact core with a half-light radius of less than 100 pc, an actively star-forming disc with a radius of about 400 pc and a star-forming clump, all of which show distinctive star-formation histories. The central stellar mass density of this galaxy is within a factor of 2 of the most massive present-day ellipticals, while being globally 1,000 times less massive. The radial profile of the specific star-formation rate is rising towards the outskirts. This evidence suggests a detection of the inside-out growth of a galaxy as a proto-bulge and a star-forming disc in the epoch of reionization.

Item Type	Article
Identification Number	10.1038/s41550-024-02384-8
Additional information	© 2024 The Author(s). This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/
Date Deposited	15 May 2025 15:45
Last Modified	04 Feb 2026 00:14