Ancient galaxies, so massive that they break modern cosmology, observed with JWST

Researchers have caught a snapshot of massive, ancient galaxies which has confounded science. They are too big to make sense of our current understanding of the universe.

“We’ve never observed galaxies of this colossal size, this early on after the Big Bang,” says Associate Professor Ivo Labbé, a researcher at Swinburne University of Technology, and lead author on a paper describing the galaxies, published in Nature.

“The six galaxies we found are more than 12 billion years old, only 500 to 700 million years after the Big Bang, reaching sizes up to 100 billion times the mass of our sun. This is too big to even exist within current models.”

If their observations are confirmed, Labbé says that the discovery “could transform our understanding of how the earliest galaxies in our Universe formed”.

The researchers are currently doing follow-up measurements to verify their findings, and rule out other explanations for them.

“One alternative [explanation], equally fascinating, is that some of the objects belong to a new class of emerging supermassive black holes, never seen before,” says Labbé.

The research was done with some of the James Webb Space Telescope (JWST)’s first research images, taken in July last year shortly after the telescope began operating.

They were taken with JWST’s Near Infrared Camera, and cross-checked against Hubble Space Telescope imagery.

“We expected only to find tiny, young, baby galaxies at this point in time, but we’ve discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe,” says co-author Assistant Professor Joel Leja, an astrophysicist at Penn State university, US.

“This is our first glimpse back this far, so it’s important that we keep an open mind about what we are seeing,” says Leja.

“While the data indicates they are likely galaxies, I think there is a real possibility that a few of these objects turn out to be obscured supermassive black holes.

“Regardless, the amount of mass we discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought. Even if we cut the sample in half, this is still an astounding change.”

The observations could be confirmed with the same JWST camera, taking deeper and more detailed pictures of the region.

“We’ve been informally calling these objects ‘universe breakers’ — and they have been living up to their name so far,” says Leja.

“This initial discovery may just be the start of a transformation in how we make sense of the world around us,” says Labbé.