Thursday, September 29, 2022

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

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

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

“We are seeing potentially the most distant starlight that anyone has ever seen,” he said.

The farther away objects are from us, the longer it takes for their light to reach us, and so gazing back at the distant universe means looking into the deep past.

Although GLASS-z13 existed in the early epoch of the universe, its exact age remains unknown as it could have formed at 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 finding was not disclosed in the first image set published by NASA last week.

When translated from the infrared to the visible spectrum, the galaxy appears as a blob of red with white at its center, as part of a wider image of the distant universe known as the “dark field”. goes.

Naidu and his colleagues – a team of a total of 25 astronomers from around the world – have 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 has yet to be peer-reviewed – but it has already rattled the global astronomy community.

“Astronomy records are already crumbling, and more volatile,” tweeted NASA Chief Scientist Thomas Zurbuchen.

“Yes, I’m only happy when the science produces clear peer-reviewed results. But, it looks very promising,” he said.

Naidu said another team of astronomers, led by Marco Castellano, who worked on similar data, had obtained similar findings, “so that we can have confidence”.

‘work to be done’

One of Webb’s great promises is the ability to find the oldest 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 spread through the vastness of the universe and shifted into the infrared region of the light spectrum, which Webb has been able to detect with unprecedented clarity. is equipped.

Naidu and his colleagues looked through this infrared data from the distant universe to discover a telltale signature of extremely distant galaxies.

Below a particular range of infrared wavelengths, all photons – packets of energy – are absorbed by the neutral hydrogen of the universe that lies between the object and the observer.

Using data collected through different infrared filters pointed at the same region of space, they were able to trace where these drop-offs in photons occurred, allowing them to predict the presence of these most distant galaxies. guessed.

“We discovered all of the earliest data for galaxies with this very fascinating signature, and these were the two systems that had the most compelling signature ever,” Naidu said.

One of these is GLASS-z13, while the other, not as ancient, is GLASS-z11.

“There is strong evidence, but work is still to be done,” Naidu said.

Specifically, the team wants to ask Webb’s managers for the telescope’s time to perform spectroscopy — the analysis of light that reveals detailed properties — to measure its precise distance.

“Right now, our estimate for distance is based on what we don’t see – it would be great to answer what we see,” Naidu said.

However, the team has already unearthed surprising properties.

For example, the Milky Way has the mass of a billion suns, which is “potentially pretty amazing, and it’s something we don’t really understand” given how long after the Big Bang it formed, Naidoo said. he 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.

© Agence France-Presse

Nation World News Desk
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