Early galaxies seeded universe with heavy elements 500 million years after Big Bang

October 2, 2026 at 05:07 PM1 min

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Astronomers at the University of Arizona found that galaxies 500 million years after the Big Bang were already dispersing carbon and oxygen into surrounding space. The study, published in Nature Astronomy, used JWST observations of three galaxies from the Epoch of Reionization. The findings challenge the view that the early universe's gas was nearly pristine.

Key Facts

The study, led by the University of Arizona and published in Nature Astronomy, examined three galaxies whose light traveled more than 13 billion years.
Observations show these galaxies as they appeared roughly 500 million years after the Big Bang, during the Epoch of Reionization.
The galaxies were already dispersing heavy elements such as carbon and oxygen into surrounding space, according to first author Yongda Zhu.
Researchers used the galaxies themselves as background light sources to detect absorption patterns of specific elements.

Heavy Element Escape

The earliest universe contained mostly hydrogen and helium, the two simplest elements. Stars formed from this material and, through nuclear fusion, created heavier elements such as carbon and oxygen. When stars died, including as supernovae, they released these elements into space. The new study shows that this process of heavy element escape began much earlier than previously expected.

JWST Observations

Zhu and colleagues focused on three extremely distant galaxies whose light has traveled for more than 13 billion years. The observations show the galaxies as they appeared roughly 500 million years after the Big Bang, during the Epoch of Reionization. During this era, the first generations of stars and galaxies ionized hydrogen gas between galaxies, ending the cosmic dark ages. The team used the galaxies themselves as background light sources, analyzing absorption patterns to detect specific elements.