Astronomers have spotted a surprising signature of oxygen in a faint galaxy that dates back to the universe’s infancy—when it was less than 300 million years old. It’s the earliest sign of oxygen found in the universe thus far.
The galaxy, named JADES-GS-z14-0 and discovered in 2024, appears far more mature than expected for such an early era, prompting astronomers to rethink how quickly galaxies evolve in the aftermath of the Big Bang.
“It is like finding an adolescent where you would only expect babies,” says Sander Schouws, a Ph.D. candidate at Leiden Observatory and first author of the Dutch-led study accepted for publication in The Astrophysical 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.”
Baby Galaxy Acting Like a Teenager
The detection of oxygen carries profound implications for understanding cosmic history. Elements heavier than helium, often referred to by astronomers as “metals”, do not appear until stars produce them in their cores. After these stars die—often in violent supernova events—the metals scatter into surrounding gas. Catching heavy metals like oxygen so early means these stellar birth-and-death cycles must have happened less than 300 million years after the Big Bang.
The presence of oxygen implies at least one generation of stars in JADES-GS-z14-0 must have already formed, lived, and died. This is far sooner than many scientists believed possible.
“I was really surprised by this clear detection of oxygen in JADES-GS-z14-0. It suggests galaxies can form more rapidly after the Big Bang than had previously been thought,” said Gergö Popping, an ESO astronomer at the European ALMA Regional Center who did not take part in the studies.
The trail began when the James Webb Space Telescope (JWST) first detected a faint glow from an extraordinarily distant source. JWST primarily observes infrared light, peering through the veil of early-universe gas and dust. Scientists noticed a distinctive drop in light at certain infrared wavelengths, indicating thick clouds of hydrogen were absorbing it. Such a finding suggested a high “redshift” value, a common measure of distance in an expanding universe.
Although JWST’s data hinted strongly at a galaxy existing 13.4 billion light-years away, astronomers needed to confirm both the distance and the chemicals present. To do so, researchers utilized the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. ALMA detects signals at radio-like wavelengths, homing in on the unique “fingerprints” emitted or absorbed by different elements.
The ALMA findings were surprising, as at 300 million years old, the young universe wasn’t mature enough to contain galaxies with heavy elements, like oxygen. Instead, they found JADES-GS-z14-0 had approximately 10 times more 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 of the paper accepted for publication in Astronomy & Astrophysics. “The evidence that a galaxy is already mature in the infant universe raises questions about when and how galaxies formed.”
Dust—or Lack Thereof
But that wasn’t the only surprising detail that emerged. ALMA found little sign of dust in the galaxy. Dust grains typically form when stars die, and they can glow at infrared or millimeter wavelengths. According to standard models, rapid star formation should also produce dust. One possibility is that there simply has not been enough time to generate large amounts. Alternatively, intense radiation from newborn stars might be dispersing the dust before it settles.
Either scenario provokes fresh questions about how dust and heavier elements like oxygen accumulate in galaxies this close to the Big Bang. Observers often rely on dust signals as a clue to star formation rates and galactic evolution, but JADES-GS-z14-0’s muted dust glow suggests new models may be needed.
These breakthroughs will likely inspire further investigations of other possible early galaxies, many of which JWST has already identified. Researchers already said they plan to use the combined power of JWST and ALMA to examine their chemical makeup, searching for more signs of oxygen and other heavier elements.
