JWST’s in-depth observations show that the first galaxies evolved faster and were less chaotic; This challenges previous theories of galaxy evolution. A new study has shown that the universe’s first galaxies were less turbulent and evolved faster than previously thought. This study, led by an international team from Durham University, used the James Webb Space Telescope (JWST) to look for evidence of the formation of bars when the universe was only a few billion years old.

These findings were published in a journal Monthly Notices of the Royal Astronomical Society.

James Webb Space Telescope article

Bars are long bands of stars found in disk or spiral galaxies such as the Milky Way. As the rods develop, they push gas into the galaxy’s central region, regulating star formation in the galaxy. Their presence tells scientists that galaxies have entered a stable and mature phase.

Previous studies using the Hubble Space Telescope had found that galaxies formed bars as far back as eight to nine billion years ago. However, JWST’s increased sensitivity and wider wavelength range allowed astronomers to detect these events further into the past.

“Galaxies in the early universe are evolving much faster than we thought. This is a real surprise because at this stage one would expect the universe to be very turbulent, with lots of collisions between galaxies and lots of gas that has not yet formed into stars,” explains study author Ph.D. Zoe Le Conte. Center for Extragalactic Astronomy, School of Physics, Durham University.

“But thanks to the James Webb Space Telescope, we see many of these bars much earlier in the life of the universe, meaning that galaxies are at a more established stage in their evolution than previously thought,” he adds. This new evidence suggests that theories about the early evolution of galaxies may need serious revision, the researchers say.

Research methodology and results

Researchers used JWST to investigate the formation of bars in galaxies that may have been observed between 8 and 11.5 billion years ago. The universe itself is 13.7 billion years old. The researchers found that of the 368 disk galaxies observed, almost 20 percent had bars; this was twice the number observed by Hubble.

Co-author Dr. D., from the Center for Extragalactic Astronomy in the Department of Physics at Durham University. Dimitri Gadotti said: “We found that there were many more bars in the early Universe than previously detected in Hubble studies, meaning that the bar-driven evolution of the galaxy occurred over a much longer period of time than previously thought.”

“Simulations of the universe now need to be carefully examined to see whether we can get the same results as the observations we made with James Webb,” Gadotti adds. “We must think beyond what we think we know.”

As the researchers looked further into the past, they could see fewer and fewer bar-forming galaxies. They say this may be because galaxies in the early universe were not that well formed. It is currently impossible to see shorter star bands that are not so easy to see, despite the increased telescopic power offered by JWST.

Future directions

Researchers say they now want to investigate more galaxies in the early universe and see if they also form bars. They hope to eventually look back to 12.2 billion years ago to look at how the rods grew over time and what mechanisms were behind that growth.