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No, the James Webb Space Telescope hasn’t found the ‘oldest galaxy’ ever

If you’ve been following the astronomical community on Twitter or space news in general, you’ve probably come across a story about the James Webb Space Telescope’s latest discovery: the “oldest galaxy we’ve ever seen.”

This is exactly what the James Webb Space Telescope promised us. Just a week ago, the first stunning images were revealed. Today, the telescope begins work on its myriad science programs, but researchers have already had access to a ton of data collected during the JWST commissioning phase and released in advance to researchers around the world.

This is how scientists ended up finding “the oldest galaxy” so quickly. They scoured a particular dataset for distant galaxies and found a candidate they named GL-z13, after the current confirmed record holder, GNz11.

There is still work to be done to confirm that GL-z13 is indeed the new record holder – in particular, it will take more time to point the Webb at the galaxy – but several publications have already crowned this galaxy universal champion.

Is it “the oldest galaxy” ever seen?

In the past 24 hours, two different research groups have uploaded articles to arXiv (one here, the other here) detailing their search for very distant galaxies in the James Webb data.

The “arXiv” site is a preprint repository, a place where scientists deposit their studies so that they can be quickly disseminated to their peers. This is a great place to quickly disseminate new research, especially in the field of astronomy and astrophysics. Nevertheless, results have generally not been peer reviewedwhich is an important checkpoint for validating the study and its methods.

Without trying to “denigrate” GL-z13, we must nevertheless show a little bit of caution. By reporting results with such certainty, the public may lose faith in scientists if GL-z13 turns out to be something else entirely. Several astronomers think the data is quite compelling and that the galaxy probably resides very (very) far away, but until there is confirmation, GL-z13 cannot take the title of “oldest galaxy”.

A misleading title

GL-Z13 isn’t really “the oldest galaxy in the world” — it’s from a time when the universe was just 330 million years old. The light of this galaxy? Yes, she is very old. She has come a long way to reach the JWST. But the galaxy itself, if confirmed, is likely the youngest galaxy ever seenaccording to Nick Seymour, an astrophysicist at Curtin University in Western Australia.

“330 million years after the Big Bang, it can’t be more than 100 million years old at best,” Seymour said. “Therefore, this is really a small galaxy at the dawn of time.”

Enthusiasm for record-breaking space exploits is a given. But to report new findings, it is important to convey uncertainty. In headlines, in social posts, in the way we discuss scientific progress. We have to set the right benchmark and leave this uncertainty. The GL-z13 story is wonderful, and it’s only just begun. Astronomers now have to study it a lot more to make sure the distances are correct.

“There’s obviously a lot of follow-up work to be done, but this is really kind of a glimpse into the future of James Webb,” said Michael Brown, an astrophysicist at Monash University.

It wasn’t until April, before Webb scoured the cosmos, that astronomers announced they had discovered perhaps the most distant galaxy yet, HD1. This galaxy is thought to date from a time when the universe was around 330 million years old. Mr Brown remarked at the time that care should be taken before handing over the title of HD1, as the data could point to a galaxy billions of light-years closer to Earth. To confirm its distance, just like for GL-z13, scientists need more observations.

We’re fascinated by breaking records, but perhaps the most interesting point of all of this is that if Webb performs as well as expected (and he appears to perform better than scientists dreamed), the title of “more ancient galaxy” will change hands regularly. New galaxies even further back in time will be discovered at a rate we could not dream of.

If this is the case, the record should not take long to fall. article adapted by CNETFrance

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