CAPE CANAVERAL, Fla. — NASA’s Webb Space Telescope discovers bright, early galaxies that have been hidden from sight until now, including one that may have formed just 350 million years after the Big Bang that created Earth. cosmos.
Astronomers said Thursday that if the results are verified, this host of newly discovered stars would beat the most distant galaxy identified by the Hubble Space Telescope, a record holder that formed 400 million years after the start of the universe.
Launched last December as a successor to Hubble, the Webb telescope provides observations indicating that stars may have formed earlier than previously thought – possibly a few million years after the creation of the universe.
Webb’s latest findings were detailed in the Astrophysical Journal Letters by an international team led by Rohan Naidu of the Harvard-Smithsonian Center for Astrophysics. The article details two exceptionally bright galaxies, the first thought to have formed 350 million years after the Big Bang and the other 450 million years after.
The extreme brightness points to two intriguing possibilities, astronomers said Thursday during a NASA press call.
The first is that these galaxies are very massive, with many low-mass stars like today’s galaxies, and must have started forming 100 million years after the Big Bang.
This is 100 million years earlier than what is currently thought to be the end of what is known as the Cosmic Dark Age, when the universe contained only gas and dark matter.
A second possibility is that they are made of “Population III” stars, which have never been observed but which, according to the theory, were only made of helium and hydrogen, before the existence heavier elements.
Because these stars burned so brightly at extreme temperatures, the galaxies formed from them would not need to be so massive to account for the brightness seen by Webb, and could have started forming later.
“We’re seeing such bright, bright galaxies right now, that we’re really unsure what’s going on here,” paper co-author Garth Illingworth of the University of California, Santa Cruz told reporters. .
Although some researchers report having discovered galaxies even closer to the creation of the universe 13.8 billion years ago, these candidates have not yet been verified, the scientists pointed out.
“It’s a very dynamic time,” said Illingworth, co-author of the paper. “There have been many preliminary announcements of even older galaxies, and we are still trying to determine as a community which of these are likely to be real.”
He said disentangling the two competing hypotheses would be a “real challenge”, although the idea of Population III was more appealing to him, as it would not require upsetting existing cosmological models.
Tommaso Treu of the University of California, Los Angeles, chief scientist of Webb’s science program, said the evidence presented so far “is as strong as it gets” for the galaxy that formed 350 million after the Big Bang. The galaxy, called GLASS-z12, now represents the most distant starlight ever seen.
If the findings are verified and more early galaxies become available, Naidu and his team wrote that Webb “will prove very effective in pushing the cosmic frontier to the brink of the Big Bang.”
“When and how the first galaxies formed remains one of the most intriguing questions,” they said in their paper.
Teams hope to soon use Webb’s powerful spectrography instruments – which analyze light from objects to reveal their detailed properties – to confirm the distance of galaxies and better understand their composition.
Webb can detect infrared light at a much higher resolution than any instrument before it.
The $10 billion observatory – the world’s largest and most powerful telescope ever sent into space – sits in solar orbit 1.6 million kilometers from Earth.
Full science operations began over the summer, and NASA has since released a series of dazzling snapshots of the universe.
The rapid discovery of galaxies defied expectations that Webb would need to survey a much larger volume of space to find such cosmic wonders.
“It’s a bit surprising that so many formed so early,” added astrophysicist Jeyhan Kartaltepe of the Rochester Institute of Technology.
NASA’s Jane Rigby, project scientist with Webb, noted that the galaxies were “hiding just below the limits of what Hubble could do.”
“They were waiting for us right there,” she told reporters. “So it’s a nice surprise that there are a lot of these galaxies to study.”
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