The James Webb Space Telescope may have already found the oldest galaxy ever seen.


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Just a week after the world was shown its first images, the James Webb Space Telescope may have discovered a galaxy that existed 13.5 billion years ago, a scientist who analyzed the data said Wednesday.

The galaxy, known as GLASS-z13, dates back 300 million years after the Big Bang, about 100 million years earlier than anything previously identified, Rohan Naidoo of the Harvard Center for Astrophysics told AFP.

“We are potentially looking at 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 thus to look into the distant universe is to look into the deep past.

Although GLASS-z13 existed in the earliest 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 discovered in so-called “early releases” of data from the orbiting observatory’s main thermal imager, called NIRcam, but the discovery was not revealed in the first set of images released by NASA last week.

Translated from infrared to visible light, the galaxy appears as a red spot with a white center, part of a larger image of deep space called the “deep field”.

Naidoo and his colleagues — a team of 25 astronomers from around the world — have submitted their findings to a scientific journal.

At the moment, the study is hosted on the preprint server, so it has a caveat that it has not yet been peer-reviewed, but it has already caused an uproar in the global astronomical community.​

“Astronomical records are already breaking, and even more reeling”, tweeted NASA Chief Scientist Thomas Zurbuchen.

“Yes, I tend to rejoice only when science gives a clear expert assessment. But it looks very promising,” he added.

Naidu said that another group of astronomers led by Marco Castellano, who worked with the same data, came to similar conclusions, “which gives us confidence.”

“Work to be done”

One of Webb’s big promises is its ability to find the earliest galaxies that formed after the Big Bang, 13.8 billion years ago.

Because they are so far from Earth, by the time their light reaches us, it has been stretched out by the expansion of the universe and shifted into the infrared region of the light spectrum, which Webb is able to detect with unprecedented clarity.

Naidoo and his colleagues combed through this infrared data from the distant universe, looking for signatures of very distant galaxies.

Below a certain threshold wavelength of infrared radiation, all photons – energy packets – are absorbed by the neutral hydrogen of the Universe, located between the object and the observer.

Using data collected through different infrared filters aimed at the same region of space, they were able to determine where this photon dip occurs, from which they infer the presence of these most distant galaxies.

“We looked for all the early data on galaxies with this very bright feature, and these were the two systems that had the most compelling feature,” Naidoo said.

One of them is GLASS-z13, and the other, not so ancient, is GLASS-z11.

“There is strong evidence, but there is still a lot to be done,” Naidoo said.

Specifically, the team wants to ask Webb’s managers for the telescope’s time to conduct spectroscopy – an analysis of light that reveals detailed properties – to measure the exact distance to it.

“Right now, our guess at distance is based on what we don’t see — it would be great to have an answer for what we see,” Naidoo said.

However, the team has already discovered surprising properties.

For example, the galaxy has a mass of a billion suns, which is “potentially very surprising and something we don’t really understand” considering how soon after the Big Bang it formed, Naidoo said.

Launched last December and fully operational since last week, Webb is the most powerful space telescope ever built, and astronomers are confident it will usher in a new era of discovery.

© Agence France-Presse

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