© Webb Space TelescopeInfrared image from JWST taken by NIRCam for the JWST Advanced Deep Extragalactic Survey program.
The James Webb Space Telescope has detected traces of carbon in one of the earliest galaxies ever observed.
This discovery suggests that a key ingredient for life emerged much sooner than we previously thought — a mere 350 million years after the Big Bang.
The galaxy in question, GS-z12, is a very distant, high-redshift galaxy that existed when the universe was just a toddler. Using JWST's powerful Near Infrared Spectrograph (NIRSpec), an international team of astronomers analyzed the light from this ancient galaxy. They broke it down into a spectrum that revealed the unmistakable chemical fingerprint of carbon.
"We were surprised to see carbon so early in the universe, since it was thought that the earliest stars produced much more oxygen than carbon," said Roberto Maiolino, a professor of experimental astrophysics at the University of Cambridge and a co-author of the study, in a statement.
The cosmic delivery service
Astronomers once believed that the production and distribution of "metals" — elements heavier than hydrogen and helium — was a gradual process, taking billions of years to unfold.
Apart from hydrogen, helium, and tiny amounts of lithium, every other element that makes up the universe formed inside a star. These elements were scattered across the cosmos by violent supernova explosions, a cosmic delivery service, seeding the next generation of stars.
However, the presence of carbon in GS-z12 challenges this long-held assumption. "Earlier research suggested that carbon started to form in large quantities relatively late - about one billion years after the Big Bang," Maiolino explained. "But we've found that carbon formed much earlier — it might even be the oldest metal of all."
A new origin story
The implications of this discovery are far-reaching. Carbon is a fundamental building block of life as we know it, essential for the formation of organic molecules. Its presence so early in the universe's history raises numerous questions about the nature of life's origins.
"These observations tell us that carbon can be enriched quickly in the early universe," said Francesco D'Eugenio, an astrophysicist at the Kavli Institute for Cosmology and the study's lead author.
"And because carbon is fundamental to life as we know it, it's not necessarily true that life must have evolved much later in the universe. Perhaps life emerged much earlier — although if there's life elsewhere in the universe, it might have evolved very differently than it did here on Earth."
While the precise mechanisms that led to the early formation of carbon remain uncertain, the researchers suggest that the very first stars may have operated differently than previously thought. They could have collapsed with less energy and allowed carbon from their outer shells to escape more readily.
"The very first stars are the holy grail of chemical evolution," Dr D'Eugenio added. "Since they are made only of primordial elements, they behave very differently to modern stars. By studying how and when the first metals formed inside stars, we can set a time frame for the earliest steps on the path that led to the formation of life."
The team's findings were published in the preprint journal arXiv, and have been accepted for publication in the journal Astronomy & Astrophysics.
More information:
Francesco D'Eugenio et al. 'JADES: Carbon enrichment 350 Myr after the Big Bang.' Astronomy & Astrophysics (in press). DOI: 10.48550/arXiv.2311.09908
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