Astronomers analysing some of the first scientific data released by the James Webb Space Telescope (JWST) have already seen something they weren鈥檛 expecting. A deep view of the early universe appears to show a surprisingly high number of disc-shaped galaxies, rather than a large number of clumpy, irregular ones. This suggests that the disc structures in certain galaxies, including the Milky Way, may have formed more rapidly than current theories predict.
at the University of Nottingham, UK, and his colleagues looked at galaxies within JWST鈥檚 鈥渄eep-field鈥� image of the galaxy cluster SMACS J0723.3-7327. The researchers examined several hundred of these distant galaxies, which existed a couple of billion years after the big bang, by eye and with the aid of computers in order to classify them into their different shapes.
Previous work using data from Hubble Space Telescope observations and computer modelling indicated disc-shaped galaxies should only account for about five per cent of the sample studied in this new JWST image 鈥� but the team actually found roughly half the galaxies scrutinised were disc-shaped.
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The result, if confirmed by further, more extensive, surveys, could mean that the disc structure in galaxies we see around us today emerged far earlier than astrophysicists imagined.
This is because disc shapes are generally thought to arise when galaxies have had a long time to settle down after an earlier, tumultuous period of collisions and mergers 鈥� one that is associated with irregular-shaped galaxies, the kind astronomers thought they would see more of.
That, says Ferreira, has 鈥渉uge implications鈥� for the models that astrophysicists currently use to explain how galaxies are born and evolve. 鈥淭his is a clue already that something鈥檚 off,鈥� he says.
There could also be wider implications for cosmological models of the expansion of the universe, dark matter and dark energy, which often include predictions for how galaxies evolve over time. 鈥淚f the models can鈥檛 predict the formation of galaxies, the models [are] not actually correct,鈥� says Ferreira.
at Lancaster University, UK, says this early result from JWST data is 鈥渞eally interesting work鈥� that is 鈥減otentially going to hold up鈥�. She says JWST鈥檚 upgraded abilities over Hubble may be key to the unexpected observations. 鈥淭he mirror for JWST is two and a half times bigger than the mirror from Hubble,鈥� says Simmons. 鈥淚t鈥檚 just a bigger light-bucket, so you can get a really deep image much faster.鈥�
In order to confirm the new result, Simmons says astronomers will need to analyse light from the galaxies to see if they are spinning in the way discs are expected to rotate 鈥� something that should be well within the capabilities of JWST鈥檚 instruments.
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