Free Astronomy Magazine May-June 2025

35 MAY-JUNE 2025 more chemically mature than ex- pected. “It is like finding an adoles- cent where you would only expect babies,” says Sander Schouws, a PhD candidate at Leiden Observa- tory, the Netherlands, and first au- thor of the Dutch-led study ac- cepted for publication in The Astro- physical Journal . “The results show the galaxy has formed very rapidly and is also maturing rapidly, adding to a growing body of evidence that the formation of galaxies happens much faster than was expected.” Galaxies usually start their lives full of young stars, which are made mostly of light elements like hydrogen and helium. As stars evolve, they create heavier elements like oxygen, which get dispersed through their host galaxy after they die. Researchers had thought that, at 300 million years old, the Universe was still too young to have galaxies ripe with heavy elements. However, the two ALMA studies indicate JADES-GS-z14- 0 has about 10 times more heavy el- ements than expected. “I was astonished by the unexpected results because they opened a new view on the first phases of galaxy evolution,” says Stefano Carniani, of the Scuola Normale Superiore of Pisa, Italy, and lead author on the paper accepted for publication in Astron- omy & Astrophysics . “The evidence that a galaxy is already mature in the infant Universe raises questions about when and how galaxies formed.” The oxygen detection has also allowed astronomers to make their distance measurements to JADES-GS-z14-0 much more accurate. “The ALMA detection offers an ex- traordinarily precise measurement of the galaxy’s distance down to an un- certainty of just 0.005 percent. This level of precision — analogous to being accurate within 5 cm over a distance of 1 km — helps refine our understanding of distant galaxy properties,” adds Eleonora Parlanti, a PhD student at the Scuola Normale Superiore of Pisa and author on the Astronomy & Astrophysics study. “While the galaxy was originally dis- covered with the James Webb Space Telescope, it took ALMA to confirm and precisely determine its enormous distance,” says Associate Professor Rychard Bouwens, a member of the team at Leiden Observatory. “This shows the amazing synergy be- tween ALMA and JWST to reveal the formation and evolution of the first galaxies.” Gergö Popping, an ESO astronomer at the European ALMA Regional Centre who did not take part in the studies, says: “I was really surprised by this clear detection of oxygen in JADES-GS-z14-0. It sug- gests galaxies can form more rapidly after the Big Bang than had pre- viously been thought. This result showcases the important role ALMA plays in unraveling the conditions under which the first galaxies in our Universe formed.” T he inset in this image shows JADES-GS-z14-0 –– the most dis- tant known galaxy as of today –– as seen with the Atacama Large Mil- limeter/submillimeter Array (ALMA). The two spectra shown here result from independent analysis of ALMA data by two teams of astronomers. Both found an emission line of oxy- gen, making this the most distant detection of oxygen, when the Uni- verse was only 300 million years old. [ALMA (ESO/NAOJ/NRAO)/S. Carni- ani et al./S. Schouws et al/JWST: NASA, ESA, CSA, STScI, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA)] !