These 70 dusty galaxies at the edge of our universe could rewrite our understanding of the cosmos

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"These galaxies are very old, which means stars were being formed in the early universe, earlier than our current models predict."

A grid showing 18 dusty galaxies that look like reddish splotches and golden splotches.
18 dusty "missing link" galaxies seen by the JWST and ALMA. (Image credit: UMass Amherst)

Using the James Webb Space Telescope and the Atacama Large Millimeter/sub-millimeter Array , astronomers have investigated 70 dusty, star-forming galaxies at the very edge of the universe. These galaxies, seen as they were less than 1 billion years after the Big Bang, could change everything we know about cosmic evolution.

It seems these galaxies were already rich in "metals," the term astronomers use to describe elements heavier than hydrogen and helium, despite existing before current models predict the current generation of stars could have forged and distributed those heavy elements.

The research into these galaxies began when Zavala and colleagues used the Atacama Large Millimeter/sub-millimeter Array (ALMA), an array of 66 radio antennas located in the Atacama Desert region of northern Chile, to identify a population of 400 bright and dusty galaxies.

Further investigation with the James Webb Space Telescope (JWST) whittled these galaxies down to 70 faint dusty galaxy candidates on the very edge of the cosmos, the majority of which had never been seen before. Combining JWST and ALMA observations, the researchers then confirmed these galaxies had formed as long ago as 500 million years after the Big Bang.

That not only suggests that our story of cosmic history needs revision, but it also connects these galaxies to two other families of strange galaxies. These are extremely bright, star-birthing galaxies discovered in the early universe by the JWST and older galaxies that have "died" and are no longer forming stars.

"It's as if we now have snapshots of the lifecycle of these rare galaxies," Zavala said. "The ultrabright ones are young galaxies, the quiescent ones are in their old age, and the ones we found are young adults."

More research will be needed to link these three populations of galaxies. However, if they are connected, then it is clear that something is missing from our understanding of galactic evolution, and the development of stars must begin earlier in the cosmos than currently theorized.

The team's results were published on Tuesday (Feb. 17) in The Astrophysical Journal Letters.

Robert Lea
Robert Lea
Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

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