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The James Webb Space Telescope spotted one of the first galaxies formed after the big bang, about 350 million years after the universe began.
The galaxy, called GLASS-z12, and another galaxy formed about 450 million years after the big bang, were discovered over the summer, shortly after the mighty space observatory began its infrared observations of the cosmos .
Webb’s ability to look deeper into the universe than other telescopes reveals previously hidden aspects of the universe, including surprisingly distant galaxies such as these two discoveries.
This discovery could change the way astronomers understand the formation of galaxies and stars in the early days of the universe.
“With Webb, we were amazed to find the most distant starlight anyone had ever seen, just days after Webb published his first data,” said Massachusetts Institute of Technology researcher astronomer Rohan Naidu. , in a press release. Naidu was lead author of a November study published in The Astrophysical Journal Letters.
Previously, the first observed galaxy was GN-z11, which existed 400 million years after the big bang and was spotted by the Hubble Space Telescope in 2016.
“As soon as we started taking data, we discovered that there were many more distant galaxies than we expected,” said Tommaso Treu, principal investigator of the GLASS-JWST Early Release science program and professor at the University of California at Los Angeles.
“Somehow the universe managed to form galaxies faster and earlier than we thought. Just a few hundred million years after the big bang, there were already a lot of galaxies. JWST has opened up a new frontier, bringing us closer to understanding how it all began. And we’ve only just begun to explore it,” said Treu, co-author of an October study in The Astrophysical Journal Letters.
The two journal studies highlighted these findings made during the Grism Lens-Amplified Survey from Space, also known as GLASS, and the Cosmic Evolution Early Release Science Survey, or CEERS.
The first galaxies discovered in this new cosmic frontier are surprising and unusual for astronomers in many ways, Treu said.
Both galaxies have sphere or disc shapes, and they are only a tiny percentage of the size of the Milky Way galaxy. Both galaxies are incredibly distant, but they are also extremely bright and very rapidly forming stars.
The research results suggest that galaxies may have started appearing in the universe just 100 million years after the big bang, which happened 13.8 billion years ago. This timeline challenges astronomers’ theories of how and when the first galaxies formed.
The early universe was chaotic and cluttered, but the structure of the two galaxies appears calm and orderly, said Erica Nelson, assistant professor of astrophysics at the University of Colorado at Boulder, co-author of the November study.
The amount of brightness in the two galaxies has puzzled scientists. One possibility is that the galaxies were massive and contained many low-mass stars, which is similar to the types of galaxies that formed later in the universe.
Or it could suggest the opposite: smaller galaxies with fewer but extremely bright stars. These bright objects, called population III stars, have long been theorized to be the first stars ever born in the cosmos.
The first stars in the universe would have been blazing with heat and composed only of hydrogen and helium. Later stars contain heavier elements that were created when the first stars exploded. So far, no population III star has ever been seen in our local universe.
But telescopes capable of peering into the distant universe, effectively looking back in time, may one day see the first Population III stars. The older of the two galaxies, GLASS-z12, could even contain Population III stars, said Adriano Fontana, a member of the GLASS-JWST team and co-author of the October study.
The new findings on the two galaxies could mean that there are other bright galaxies waiting to be found in the distant universe.
Galaxy distance estimates are based on Webb’s infrared detection. Follow-up spectroscopic observations can confirm how long their light has been stretched across the universe, as well as the rate of star formation in each galaxy and the elements those stars contained.
Webb’s near-infrared spectrograph will capture data that could lead to this information.
“These sightings just blow your mind. It’s a whole new chapter in astronomy. It’s like an archaeological dig, and suddenly you find a lost city or something you didn’t know about. It’s just astounding,” said Paola Santini, a researcher at the Astronomical Observatory at the National Astrophysical Institute in Rome, who was a co-author of the October study.
The Webb Telescope entered its fifth month of science operations and was found to be more powerful and capturing sharper images than pre-launch expectations, said Dr Jane Rigby, Webb Operations Project Scientist at Goddard Space NASA Flight Center in Greenbelt, Maryland.
“These galaxies we’re talking about are bright,” Rigby said. “They were hiding just below the limits of what Hubble could do. They were just there waiting for us. We just had to go a little redder and go further than Hubble could do. »
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