The James Webb Space Telescope has spotted a giant galaxy that shouldn’t exist.
Using this exceptionally powerful telescope, a team of researchers were able to peer back in time and observe this never-before-seen spiral galaxy, dubbed the Big Wheel, as it looked just two billion years after the Big Bang.
The farther out in space astronomers look using telescopes like the James Webb, the further back in time they’re seeing, almost all the way to the Big Bang itself.
A two-billion-year-old galaxy is considered young on a cosmic scale, but the Big Wheel’s size at that point in history suggested that it should have been much older.
The researchers determined that this galaxy stretched nearly 98,000 light years across, roughly the same size as our much-older home galaxy, the Milky Way, is today.
Based on experts’ current understanding of the early universe, it would be highly unlikely for a galaxy to achieve the Big Wheel’s size in just two billion years.
Study co-author Themiya Nanayakkara, an astronomer at Swinburne University of Technology in Australia, said: ‘You have to remember that the Milky Way has had another 10 billion years or so to grow than the Big Wheel.’
He and his colleagues concluded that the Big Wheel was the largest two-billion-year-old galaxy ever observed, and is likely much bigger than the Milky Way is today – roughly 10 billion years later.
Using JWST, researchers observed the newly discovered Big Wheel Galaxy as it looked just two billion years after the Big Bang. But its size suggests it should have been much older
This presents a puzzling question: how did this galaxy manage to grow so enormous in such a relatively short amount of time?
‘Finding one of these galaxies is not a problem for cosmological theories, because one could be an outlier, but if we keep finding more, then I think we may have to say ‘Okay, our models might need some refining,” Nanayakkara told New Scientist.
But he has a theory that could explain how the Big Wheel managed to grow so rapidly without breaking the laws of the universe as we understand them.
It posits that multiple galaxies collided and merged in quick succession to form one large spiral galaxy, accelerating the growth rate that usually results from the gradual gathering of gas and dust in space.
This may have been made possible by the Big Wheel’s unusually dense surroundings.
It is located in a region of space where galaxies are packed tightly together, 10 times denser than typical areas of the universe, Nanayakkara wrote in an article for The Conversation.
‘This dense environment likely provided ideal conditions for the galaxy to grow quickly. It probably experienced mergers that were gentle enough to let the galaxy maintain its spiral disk shape,’ he explained.
Lead researchers Sebastiano Cantalupo (left) and Weichen Wang (right) stand beside an image of the Big Wheel. Now, the researchers will begin searching for more galaxies like it
The James Webb Space Telescope is the most powerful ever built. It allows astronomers to peer across time and space to see the earliest formations in our universe
At the same time, ‘the gas flowing into the galaxy must have aligned well with its rotation, allowing the disk to grow quickly without being disrupted. So, a perfect combination,’ Nanayakkara added.
He and his colleagues published their findings in the journal Nature Astronomy.
Finding a galaxy like the Big Wheel was like finding a needle in a haystack. According to Nanayakkara, his team had lest than a two percent chance of discovering it.
Now, the researchers will begin the hunt for more unusually large galaxies in an attempt to determine exactly how rare they are.
If they aren’t as uncommon as experts currently believe them to be, they may have to reevaluate everything they know about galaxy formation.
