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 analyzing the data said on Wednesday.
The galaxy known as GLASS-z13 dates from 300 million years after the Big Bang, about 100 million years earlier than anything previously identified, Rohan Naidu of the Harvard Center for Astrophysics told AFP.
“We’re looking at possibly the most distant starlight anyone has ever seen,” he said.
The further away objects are from us, the longer it takes for their light to reach us, and so looking back into the distant universe means looking into the deep past.
Although GLASS-z13 existed in the earliest era of the universe, its exact age is unknown as it could have formed any time within the first 300 million years.
GLASS-z13 was spotted in so-called early-release data from the orbiting observatory’s main infrared imager, called NIRcam — but the discovery was not revealed in the first set of images released by NASA last week.
Translating from the infrared to the visible spectrum, the galaxy appears as a red spot with a white center, part of a broader image of the distant cosmos dubbed the “Deep Field.”
Naidu and colleagues – a team of 25 astronomers from around the world – have submitted their findings to a scientific journal.
At the moment, the research is being published on a “preprint” server, so it comes with the caveat that it’s yet to be peer-reviewed — but it’s already had the global astronomy community in a frenzy.
“Astronomical records are already crumbling and more are shaky,” tweeted NASA chief scientist Thomas Zurbuchen.
“Yes, I tend not to cheer until the scientific results have clear peer review. But this looks very promising,” he added.
Naidu said another team of astronomers led by Marco Castellano working on the same data came to similar conclusions, “that gives us confidence.”
– ‘work to do’ –
One of Webb’s big promises is his ability to find the earliest galaxies formed after the Big Bang 13.8 billion years ago.
Because these are so far from Earth, by the time the universe expands, their light has been stretched and shifted into the infrared part of the light spectrum, which Webb can see with unprecedented clarity.
Naidu and colleagues combed this infrared data of the distant Universe in search of a telltale signature from extremely distant galaxies.
Below a certain infrared wavelength, all photons—packets of energy—are absorbed by the universe’s neutral hydrogen that lies between the object and the observer.
By using data collected through different infrared filters aimed at the same region of space, they were able to see where these photon falls were occurring, from which they inferred the presence of these most distant galaxies.
“We searched all of the early data for galaxies with this very prominent 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, not so 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’s manager for telescope time to perform spectroscopy — an analysis of light that reveals detailed properties — to measure the exact distance.
“Right now, our estimate of distance is based on what we don’t see – it would be great to have an answer to what we see,” Naidu said.
However, the team has already discovered surprising properties.
For example, the galaxy has the mass of a billion suns, which “is potentially very surprising, and it’s something we don’t really understand,” given how shortly after the Big Bang it formed, Naidu said.
Webb was launched last December and has been fully operational since last week. It’s the most powerful space telescope ever built, and astronomers are confident it will usher in a new era of discovery.
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