James Webb ST's 1st Image Was Hiding a Pleasant Surprise: The Oldest Galaxy Ever Discovered

It’s been weeks since JWST started traveling into the past by taking photos of galaxies 13 billion years old or more. The telescope (JWST) has broken the record for discovering the oldest galaxy so far about almost 100 million years after the big bang.

GN-z11, the previous candidate for the most distant galaxy discovered, appears as the red object in the center of the zoom-in image. Harikane et al. One of the key goals of JWST is to see the very first galaxies formed just after the big bang 13.8 billion years ago. The current oldest galaxy - called GN-z11 found by the Hubble ST formed about 400 million years after the birth of the universe.

Astrophysicist Rohan Naidu from Harvard and his team of workers from the Smithsonian Centre of Astrophysics in Massachusetts believe they've found the oldest galaxy in a dataset of JWST which was publicly released a few weeks back - called GLASS. The Galaxy's name is GLASS-z13, this galaxy formed about 300 million years after the big bang. Rohan's team also found a second galaxy, at the same age as GN-z11.

“We found two very compelling candidates for extremely distant galaxies,” says Naidu. “If these galaxies are at the distance we think they are, the universe is only a few hundred million years old at that point.”

These two galaxies have an equivalent mass of about a billion suns at this time. That is a very unique feature only thought to have in galaxies up to 500 million years old, concludes the team, this might be a hint that the stars usually formed more rapidly than we believed in the early universe. The galaxy which is close to the big bang, Glass-z11, also started to develop a disc-like structure due to its rotation.

These new two galaxies are very small as compared to our Milky Way galaxy. (GLASS z-13 is only 1600 light-years across and z-11 is 2300 light years in comparison to Milky Way, Milky Way is some 100,000 light-years across.) Astrophysicists from Niehls Bohr Institute in Denmark, Gabriel Brammer, was also part of the GLASS team and helped his team in discovering GN-z11, explained that further study and analysis are needed to get to exact  the distance between these two galaxies. 

Only James Webb ST can achieve that.

“They’re very convincing candidates,” he says. “We were pretty confident that JWST would see distant galaxies. But we’re a little bit surprised how easy it is to detect them.”

JWST is very very strong and it should easily make discoveries like this on regular basis. It will find galaxies a lot closer to the Big bang than these two galaxies, maybe 200 million years after the big bang when the very first galaxies and stars have believed to form.

“How early does star formation start in the universe?” says Naidu. “It’s one of the last major unknowns in our broad timeline of the universe.”

Reference: arxiv.org/abs/2207.09434