Webb Telescope sees galaxies that clear the mysterious mists of the early universe

Astronomers have identified bright hydrogen emissions from galaxies in the very early universe. The surprising discovery is that researchers will challenge themselves to explain how this light pierced a thick mist of neutral hydrogen that filled the space at that time.

The key goal of the NASA/ESA/CSA James Webbspace Telescope was to see more than ever before the distant past of the universe, where the first galaxy was formed after the Big Bang, an era known as the Cosmic Dawn.

Researchers studying one of these very early galaxies have been discovered in a range of light that challenges our established understanding of the early history of the universe. Their results have been reported in Nature.

Webb has discovered the incredibly distant Galaxy Jades-GS-Z13-1, observed just 330 million years after the Big Bang. Researchers estimated redshift using galaxy brightness with various infrared filters. This measures the distance of a galaxy from Earth based on how light stretches as you travel through the expanding space.

NIRCAM imaging resulted in an initial redshift estimate of 12.9. Previously, we observed the galaxy using Webb’s near-infrared spectrograph (NIRSPEC) instruments to confirm the extreme redshift, an international team led by Dr. Joris Wittok of the Kaburi Space Institute at Cambridge University.

The resulting spectra confirmed a redshift of 13.0. This is the equivalent of a galaxy seen just 330 million years after the Big Bang, a small portion of the universe’s current age.

However, unexpected features also stood out. It is the wavelength of light of a particular clearly brighter wavelength, identified as Lyman-α 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,” said Professor Roberto Maiolino, co-author of Cabrie Space Research Institute in Cambridge. “Most of this haze was lifted up in a process called regeneration, which was completed about a billion years after the Big Bang.

“The GS-Z13-1 shows the surprisingly clear and obvious signature of the Lyman-alpha emissions, which can only be seen after the surrounding mist has been fully lifted.

Before and after reionization, neutral hydrogen fog surrounding the galaxy blocked the ultraviolet rays of released energy, similar to the filtration effect of colored glass. Such light, including the radiation of Lyman-α, could not reach Earth from these fledgling galaxies until sufficient stars were formed and hydrogen gas could ionize.

Confirming Lyman-α radiation from this galaxy has great significance in understanding the early universe. “We’ve been working hard to get the better of our lives,” said Kevin Heinlein, a co-author at the University of Arizona.

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

The source of Lyman-α radiation from this galaxy is not yet 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, which is larger, hotter, brighter, and perhaps representing the first generation of stars, than the stars formed in later epochs.” The powerful active galactic nucleus, driven by one of the first super-large black holes, is another possibility identified by the team.

The team is planning further follow-up observations of the GS-Z13-1, aiming to obtain more information about the nature of this galaxy and the origin of its powerful Lyman alpha radiation. Whatever galaxies hide, they certainly illuminate the new frontier of cosmology.