JWST has found the oldest galaxy we have ever seen in the universe

Discoveries from the James Webb Space Telescope are pouring in, with an analysis of the latest data revealing a galaxy that dates back to just 300 million years after the big bang – the oldest we have ever seen.

Just weeks into its mission, the James Webb Space Telescope (JWST) has broken the record for the oldest galaxy ever observed by nearly 100 million years.

Seeing some of the first galaxies to form after the big bang 13.8 billion years ago is one of the key goals of the JWST. When these emerged is currently unknown: the previous oldest identified galaxy, found by the Hubble Space Telescope, is called GN-z11 and dates back to 400 million years after the birth of the universe.

Rohan Naidu at the Harvard-Smithsonian Center for Astrophysics and his colleagues think they have already found an older one in a publicly released JWST data set called GLASS. Known as GLASS-z13, the galaxy dates back to just 300 million years after the big bang. The team also found a second galaxy, GLASS-z11, of a comparable age to 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.”

The two galaxies appear to have already grown the equivalent mass of a billion suns since they started forming. That is something we would expect for galaxies that have been forming for around 500 million years, says the team, possibly hinting that stars formed more rapidly than we thought in the early universe. The closer galaxy, GLASS-z11, also appears to have started to form a disc-like structure caused by its rotation.

Both galaxies are very small, GLASS-z13 being only about 1600 light years across and GLASS z-11 about 2300 light years. By comparison, our Milky Way is some 100,000 light years across.

Gabriel Brammer at the Niehls Bohr Institute in Denmark, part of the GLASS team and a co-discoverer of GN-z11, says that further analysis will be needed to confirm the distance to the two galaxies. Only JWST can do that work. “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’s immense power should make discoveries like this a regularity. Longer hunts for ancient galaxies should be able to probe much further, perhaps to less than 200 million years after the big bang, when some of the first galaxies and stars in the universe are thought to have formed.

“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.”


Post a Comment

Previous Post Next Post