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Washington (AFP) – Just a week after its first images were shown to the world, the James Webb Space Telescope may have found a galaxy that existed 13.5 billion years ago, a scientist who analyzed the data said on Wednesday.
Known as GLASS-z13, the galaxy dates back 300 million years after the Big Bang, about 100 million years earlier than anything previously identified, Harvard’s Rohan Naidu told AFP. Center for Astrophysics.
“We are potentially looking at the most distant starlight anyone has ever seen,” he said.
The farther objects are from us, the longer it takes for their light to reach us, and so to look back into the distant universe is to see into the deep past.
Although GLASS-z13 existed in the oldest era of the universe, its exact age remains unknown as it could have formed at any time during the first 300 million years.
GLASS-z13 was spotted in so-called ‘advance scatter’ data from the orbiting observatory’s main infrared imager, called NIRcam – but the find was not revealed in the first set of images released by the NASA last week.
When translated from infrared into the visible spectrum, the galaxy appears as a patch of red with white at its center, as part of a larger picture of the distant cosmos called the “deep field.”
Naidu and his colleagues – a team of 25 astronomers from around the world – submitted their findings to a scientific journal.
For now, the research is posted on a “preprint” server, so it comes with the caveat that it hasn’t yet been peer-reviewed – but it has already erupted in the global community. of astronomy.
“Astronomy records are already collapsing, and others are fragile,” NASA chief scientist Thomas Zurbuchen tweeted.
“Yes, I tend to only get excited once the scientific results have been validated by peer review. But it looks very promising,” he added.
Naidu said another team of astronomers led by Marco Castellano who worked on the same data came to similar conclusions, “so that gives us confidence.”
‘Work to do’
One of Webb’s great promises is his ability to find the first galaxies that formed after the Big Bang 13.8 billion years ago.
Because these are so far from Earth, by the time their light reaches us, it has been stretched by the expanding universe and moved into the infrared region of the light spectrum, which Webb is equipped to detect with a unprecedented clarity.
Naidu and his colleagues combed through this infrared data from the distant universe, looking for a telltale signature of extremely distant galaxies.
Below a certain infrared wavelength threshold, all the photons – the energy packets – are absorbed by the neutral hydrogen of the universe which is between the object and the observer.
Using data collected through different infrared filters pointed at the same region of space, they were able to detect where these photon falls were occurring, from which they deduced the presence of these most distant galaxies.
“We looked for all the early data on galaxies with this very striking signature, and these were the two systems that had by far the most compelling signature,” Naidu said.
One of them is GLASS-z13, while the other, less old, is GLASS-z11.
“There is strong evidence, but there is still work to be done,” Naidu said.
In particular, the team wants to ask Webb officials for time for the telescope to perform spectroscopy — an analysis of light that reveals detailed properties — to measure its precise distance.
“At the moment our distance estimate is based on what we don’t see – it would be great to have an answer for what we see,” Naidu said.
Already, however, the team has detected some surprising properties.
For example, the galaxy has the mass of a billion suns, which is “potentially very surprising, and that’s something we don’t really understand” given how quickly it formed after the Big Bang, Naidu said.
Launched last December and fully operational since last week, Webb is the most powerful space telescope ever built, with astronomers confident it will usher in a new era of discovery.
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