By Stephen Beech via SWNS
The first galaxies evolved much faster than previously thought, suggests new research.
Astronomers looked back more than 10 billion years in time to discover that the universe’s early galaxies were less chaotic and developed faster than had been believed.
Their “surprise” findings could lead to a “rethink” of theories concerning galaxy evolution in the early stages of the Universe’s formation.
An international team, led by Durham University scientists, used the James Webb Space Telescope (JWST) – the most powerful ever built – to find evidence of bar formation when the Universe was just a few billion years old.
They explained that bars are elongated strips of stars found in disc or spiral galaxies such as the Milky Way.
Study lead author Zoe Le Conte said that as bars develop, they regulate star formation within a galaxy, pushing gas into the galaxy’s central region.
She says their presence tells scientists that galaxies have entered a settled, mature phase.
Previous studies conducted using the Hubble Space Telescope had been able to detect bar-forming galaxies up to eight or nine billion years ago.
However, the increased sensitivity and wavelength range provided by the JWST enabled the research team to see the phenomenon happening still further back in time.
They say the findings, published in the journal Monthly Notices of the Royal Astronomical Society, could lead to a “rethink” of galaxy evolution theories.
Le Conte, a PhD researcher in the Centre for Extragalactic Astronomy at Durham University, said: “Galaxies in the early Universe are maturing much faster than we thought.
“This is a real surprise because you would expect the Universe at that stage to be very turbulent with lots of collisions between galaxies and a lot of gas that hasn’t yet transformed into stars.
“However, thanks to the James Webb Space Telescope we are seeing a lot of these bars much earlier in the life of the Universe which means that galaxies were at a more settled stage in their evolution than previously thought.
“This means we will have to adjust our views on early galaxy evolution.”
The researchers used the JWST to look for bar formation in galaxies as they would have been seen between eight to 11.5 billion years ago. The Universe itself is 13.7 billion years old.
Of 368 disc galaxies observed, the researchers saw that almost one in five had bars – twice as many as observed by Hubble.
Co-author Dr. Dimitri Gadotti, also of Durham’s Centre for Extragalactic Astronomy, said: “We find that many more bars were present in the early Universe than previously found in Hubble studies, implying that bar-driven galaxy evolution has been happening for much longer than previously thought.
“The fact that there are a lot more bars is what’s very exciting.”
He added: “The simulations of the Universe now need to be scrutinized to see if we get the same results as the observations we’ve made with James Webb.
“We have to think outside of what we thought we knew.”
As the researchers looked further back in time, they were able to see fewer and fewer bar-forming galaxies.
They say this might be because galaxies at an even earlier stage of the Universe might not be as well formed.
There is also currently no way to see shorter bars of stars, which are less easy to spot, even with the increased telescopic power offered by the JWST.
The researchers now want to investigate even more galaxies in the early Universe to see if they have also formed bars.
The team hopes to eventually look further back in time – 12.2 billion years – to look at bar-growth and the mechanisms behind it.
