No, the James Webb Space Telescope has not 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.”

That’s 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 scientists have already had access to a wealth of data collected during the JWST commissioning phase and released in advance to researchers around the world.

That’s 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’s still work to be done to confirm that GL-z13 is indeed the new record holder — in particular, it will take longer to point Webb at the galaxy — but several publications have already crowned this galaxy’s all-time champion.

Is it “the oldest galaxy” ever seen?

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

The “arXiv” site is a preprint repository, a place where scientists deposit their research so that it can be quickly disseminated to their peers. This is a good place to quickly disseminate new research, especially in astronomy and astrophysics. Anyway, results have generally not been peer reviewedwhich is an important control point to validate the study and its methods.

Without trying to “denigrate” the GL-z13, we still need to exercise a little 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 believe that the data is quite convincing and that the galaxy is probably very (very) far away, but until there is confirmation, the GL-z13 cannot claim 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 only 330 million years old. The light of this galaxy? Yes, she is very old. She has come a long way to reach 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 truly a small galaxy at the dawn of time.”

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

“Obviously there’s a lot of follow-up work to be done, but this is really 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 believed to originate from a time when the universe was about 330 million years old. Brown noted at the time that care should be taken before handing over the title HD1, as the data could point to a galaxy billions of light years closer to Earth. To confirm its distance, just like for the GL-z13, scientists need more observations.

We’re fascinated by record breaking, but perhaps the most interesting thing about all of this is that if Webb performs as well as expected (and he appears to be performing better than scientists dreamed), the title of “oldest galaxy” will change hands on a regular basis. 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 shouldn’t take long to fall.

CNET.com article adapted by CNETFrance

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