Oxygen detected in the most distant galaxy ever found

CNN

20-03-2025

Astronomers have made the surprising discovery of oxygen and elements like heavy metals in the most distant known galaxy. The galaxy is 13.4 billion light-years away, meaning it formed in the early days of the universe.
Astronomers believe the big bang created the universe 13.8 billion years ago.
The unusually large, luminous distant galaxy, called JADES-GS-z14-0, was initially detected in January 2024 using the James Webb Space Telescope, which observes the universe in infrared light that's invisible to the human eye. The space observatory can effectively peer back in time to the beginning of a mysterious era called Cosmic Dawn, or the first few hundred million years after the big bang when the first galaxies were born, because it can observe light that has traveled for billions of years across space to Earth.
Light from JADES-GS-z14-0 has taken 13.4 billion years to reach our corner of the universe, so Webb and other observatories such as ALMA, or the Atacama Large Millimeter/submillimeter Array in Chile's Atacama Desert, are seeing the galaxy as it was when the universe was only about 300 million years old.
When astronomers used ALMA to follow up on Webb's initial observations, they were stunned to find the presence of oxygen and heavy metals because their presence suggests that galaxies formed more quickly than expected in the early days of the universe.
The results of the ALMA detections were published Thursday in separate studies in The Astrophysical Journal and Astronomy & Astrophysics.
'It is like finding an adolescent where you would only expect babies,' said Sander Schouws, lead author of The Astrophysical Journal study and a doctoral candidate at Leiden Observatory at Leiden University in the Netherlands, in a statement. '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.'
The fact that JADES-GS-z14-0 was laden with heavy elements is causing astronomers to question what some of the earliest galaxies were really like — as well as how many more they may find using Webb and ALMA.
A bright light leads to a surprise
Multiple aspects of JADES-GS-z14-0, including its large size and brightness, have proved to be unexpected. As Webb surveyed 700 distant galaxies, this one turned out to be the third brightest despite it being the farthest, Schouws said. But the oldest galaxies are expected to be smaller and dimmer because the universe was much smaller at the time.
'In general, galaxies this early in the universe are very different from the famous galaxies we know from the beautiful images of Hubble and JWST,' Schouws said in an email. 'They are a lot more compact, rich in gas and messy/disordered. The conditions are more extreme because a lot of stars are forming rapidly in a small volume.'
Galaxies typically begin from huge gas clouds that collapse and rotate, filling with young stars that are largely made of light elements such as helium and hydrogen. As stars evolve over time, they create heavier elements such as oxygen and metals, which disperse throughout the galaxy as stars explode at the end of their lifetime. In turn, the elements released by dying stars lead to the formation of more stars as well as the planets that orbit them.
But nothing about JADES-GS-z14-0 fits that model. Instead, the galaxy contains 10 times more heavy elements than expected, the study authors said.
'Such elements are produced by massive stars and the large amount of oxygen suggests that several generations of massive stars were already born and died,' said Dr.Stefano Carniani, assistant professor at the Scuola Normale Superiore of Pisa, Italy, and lead author of the Astronomy & Astrophysics study, in a statement. 'In conclusion (JADES-GS-z14-0) is more mature than expected and these results imply that the first generation of galaxies assembled their mass very quickly.'
Going the distance
Using ALMA also enabled the researchers to confirm the distance of the galaxy, originally measured using Webb, and refine their measurements. Together, both telescopes can be used to study the formation and evolution of the first galaxies, said Rychard Bouwens, associate professor at Leiden University and coauthor of the study in The Astrophysical Journal.
'I was really surprised by this clear detection of oxygen in JADES-GS-z14-0,' said Gergö Popping, a European Southern Observatory astronomer at the European ALMA Regional Centre, in a statement. Popping did not participate in either study.
'It suggests galaxies can form more rapidly after the Big Bang than had previously been thought. This result showcases the important role ALMA plays in unraveling the conditions under which the first galaxies in our Universe formed.'
While Webb can help identify extremely distant galaxies, ALMA can zoom in to study the gas and dust within them by detecting the far-infrared light they emit, Carniani said. Studying such galaxies can help shed light on the many remaining mysteries of Cosmic Dawn, such as what occurred shortly after the universe first began and the identities of the first celestial objects to appear.
The study authors believe the early galaxies may have formed more stars, and stars on a more massive scale, than expected, which would also affect the brightness of the galaxy overall.
'It's like burning candles: you can have candles with a wide wick that have a bright flame (massive stars) or you can have candles that burn slow and efficient (normal stars),' Schouws said.
But more observations are needed to understand exactly what the researchers are seeing, he said.
The team wants to determine whether the galaxy and its rapid evolution are truly unique, or if there are more like it in the early universe since a single celestial object is not enough to establish a new model of galaxy formation, Carniani said.