Astronomers Uncover Earliest Signs of Galaxy-Building in Action

Astronomers at Durham University have made a major advance in understanding how galaxies formed and evolved in the early universe. Using powerful new observations, the team discovered the most distant example ever found of a compact, star-forming structure at the heart of a galaxy, dating back more than 9 billion years. This discovery shows that galaxies were already developing complex internal structures much earlier than scientists had assumed. The research reveals clear evidence of a "nuclear disk" (a dense, rotating disk of stars at the very center of a galaxy) forming at a time when the universe was still relatively young.

What happened

The Durham-led team made the discovery using data from the James Webb Space Telescope, whose unprecedented sensitivity and sharp resolution allow astronomers to study distant galaxies in extraordinary detail. The galaxy they studied is seen as it was just 4.5 billion years after the Big Bang. At its center, the researchers identified a nuclear disk that is actively forming new stars and still growing. Crucially, the nuclear disk appears to have been built by a long, bar-shaped structure of stars stretching across the galaxy.

These bars are a familiar feature of many present-day spiral galaxies and act like cosmic engines, driving gas and stars toward the center and helping new structures form. While previous studies had shown that bars can form early, there was no direct proof that they were already reshaping galaxies at this stage in the universe's history. This research provides that missing evidence.

Why it matters

This discovery shows that galaxies were already developing complex internal structures much earlier than scientists had assumed. The presence of a nuclear disk and a bar-shaped structure in a galaxy over 9 billion years ago indicates that the processes driving galaxy evolution were active much earlier in the universe's history than previously thought.

How to think about it

This discovery encourages a reevaluation of current models of galaxy evolution, particularly regarding the role of stellar bars and nuclear disks in shaping galaxy structures. It highlights the importance of continued exploration of the early universe using advanced observational tools like the James Webb Space Telescope.

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