Webb discovers Lyman-Alpha emissions from ancient galaxy in early universe

The light of Lyman Afa from Jades-GS-Z13-1 took us nearly 13.47 billion to contact us, as it dates back just 330 million years from the Big Bang.

NASA/ESA/CSA James Webb Space Telescope’s key scientific goal was to see more than ever before the distant past of our universe, when the first galaxy formed after the Big Bang.

This search has already led to record-breaking galaxies when observing programs such as the JWST Advanced Deep Deep Alactic Survey (Jades).

Webb’s extraordinary sensitivity to infrared also opens up a whole new path for research into when and how such galaxies were formed, and their impact on the universe of the time known as Cosmic Dawn.

Astronomers studying one of these very early galaxies have been discovered in a spectrum of light that challenges our established understanding of the early history of the universe.

The Jades-GS-Z13-1 (GS-Z13-1 for short) was discovered in images taken by Webb’s Nircam (near-infrared camera) as part of the Jades program.

Dr. Roberto Maiolino and colleagues at the University of Cambridge and London used galaxy brightness with various infrared filters to estimate the redshift that measures the distance of a galaxy from Earth, based on how light stretches along the path of a space.

NIRCAM imaging resulted in an initial redshift estimate of 12.9. In an attempt to confirm that extreme redshift, astronomers observed the galaxy using Webb’s near-infrared spectrometer (NIRSPEC) instrument.

The resulting spectrum confirmed that the redshift was 13.0. This is the equivalent of a galaxy seen just 330 million years after the Big Bang, the current 13.8 billion-year-old minority in the universe.

However, unexpected features also stood out. One is the wavelength of light of a particular distinct bright wavelength, identified as Lyman alpha radiation emitted by hydrogen atoms.

This emission was far stronger than astronomers who thought they could be possible at this early stage of space development.

“The early universe was soaked in a thick mist of neutral hydrogen,” Dr. Maiolino said.

“Most of this haze was lifted in a process called reionization, which was completed about a billion years after the Big Bang.”

“The GS-Z13-1 shows the incredibly clear and Telltail signature of the Lyman Alpha radiation, which can only be seen after the surrounding mist has been fully lifted,” he said.

“This result was completely unexpected by early galaxy formation theories, which surprised astronomers.”

“Before and during the reionization, the enormous amount of neutral hydrogen mist surrounding the galaxy blocked the ultraviolet rays of released energy, like the filtration effect of colored glass.”

“Until sufficient stars were formed and the hydrogen gas could ionize, such light, including Lyman Alpha radiation, could not escape these fledgling galaxies and reach Earth.”

“According to Lyman Alpha radiation from this galaxy has therefore had great significance in our early understanding of the universe.”

“We’ve seen a lot of people who have had a lot of trouble with the world,” said Dr. Kevin Hayneline, an astronomer at the University of Arizona.

“We could have thought that early universes were covered in dense mists that would be very difficult to find even a powerful lighthouse peering through, but here, beams of light from this galaxy penetrate the veil.”

“This fascinating emission line has a major impact on how and when the universe has been reionized.”

The source of GS-Z13-1’s Lyman Alpha radiation from this galaxy is yet to be known, but it may contain the first light from the earliest generation of stars formed in the universe.

“The large bubbles of ionized hydrogen surrounding this galaxy may have been created by the star’s unique population, much larger, hotter and brighter than the stars formed at the later epoch, and perhaps representative of the first generation of stars, said Dr. Joris Wittok, an astronomer at Cambridge and Appenhagen University.

“The powerful active galactic nucleus (AGN) driven by one of the first super-large black holes is another possibility identified by our team.”

Team’s Survey results Published in the March 26th issue of the journal Nature.

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J. Wittstock et al. 2025. We witness the onset of reionization with Lyman-α ejection in the redshift13. Nature 639, 897-901; doi:10.1038/s41586-025-08779-5