Does anyone remember GLASS-z13? Nope?
It was spotted by the James Webb Space Telescope and claimed to be the “oldest galaxy ever seen” and it was announced… six days ago.
Yes, it’s true. Not even a week ago, two preprint articles published in the arXiv (pronounced “archive”) scientific article repository detailed some of the earliest analyzes of images taken by the JWST, the body of humanity.. Two galaxies lurked in the data – potentially the most distant galaxies humans have ever seen. One of them was dubbed GLASSz-13 or GL-z13 for short. (The Atlantic gave it the cute name “Glassy.”)
“JWST has found the oldest galaxy we have ever seen in the universe,” one headline read. The story exploded on the web,and consumer outlets pick up the record discovery. He even has his own Wikipedia page.
In the rush of reporting,. It’s not the “oldest galaxy” we’ve ever seen. It may be the oldest light we have never detected but it is probably a very Young galaxy, no more than 100 billion years into its lifetime (an important distinction). It’s also important to note that GL-z13 is currently only a “candidate” that needs further investigation – the data is pretty good, according to astronomers I’ve spoken with – but further observations would help tick him off as the record holder.
But all that may not even matter.
In a slew of new papers published on arXiv on Monday, astronomers picked out galaxies that might even lie further away far than GL-z13. It’s a showcase of the power of the groundbreaking James Webb Space Telescope.
As soon as the researchers had access to Webb’s first batch of data, they began scouring it for distant galaxies. Webb is the best at finding these galaxies because he sees the cosmos in infrared light rather than visible light.
Comparison of images from the Hubble and James Webb space telescopes: see the difference
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Visible light from the earliest galaxies in the universe has been “red-shifted”. Because the universe has been expanding since the Big Bang, the wavelengths of light are stretching. When you stretch the light that we can see with our eyes, that stretch moves it to a redder wavelength. In this case, infrared. Webb is designed specifically to capture that light.
Astronomers refer to the redshift as z. Upper z the values essentially represent another look back in time. For instance, z = 1 corresponds to about 7.7 billion years, while z = 10 is about 13.2 billion years old.
In papers uploaded to arXiv, at least three presented candidate galaxies with a z value greater than 16. This would correspond to approximately 13.6 billion years. We present the case of a galaxy at z = 16.7, which would correspond to about 250 million years after the Big Bang.
Another, summarized by astrophysicist Steve Finklestein in this twitter threadpresents a galaxy to z > 14. Finkelstein named it Maisie’s Galaxy, after his daughter.
The discoveries have astronomers buzzing on Twitter again, but what about the GL-z13?
Well it is z the value is around 13 (as the name suggests), so maybe it’s Game Over for Glassy.
However, it still has a chance of becoming the most distant galaxy ever observed, as astrophysicists need to validate what they see in the JWST data.
“Many of the candidates in these articles are not as convincing [as GL-z13]”, said Michael Brown, an astrophysicist at Monash University in Melbourne. Caution is advised when looking at these distant galaxies and, through the multitude of new papers, astronomers are seeing different signals.
There’s even more uncertainty about distances when you introduce the slight disagreement among astrophysicists about how fast the universe is expanding. We will not discuss that here. But it should be noted that confirming these distant features as true galaxies will require further observations which will most likely occur during Webb’s first years of operation.
And yes, the Webb Space Telescope is poised to provide even more candidates for the most distant galaxy ever observed beyond today. They might even come across arXiv tomorrow! While many will soon fade from public consciousness, each will provide a springboard for astrophysicists to piece together the earliest moments of our universe. Some of the questions that these galaxies will answer have not even been asked yet.
In fact, astrophysicists are already discovering that the early universe could be much busier than they anticipated. Stars may have started to form at a much faster rate than some models predicted. How did matter coalesce and start forming these early galaxies? We do not know yet. But Webb is apparently already rewriting what we thought we knew about the start of it all.
It is an astronomical revolution. So buckle up. It’s going to be one hell of a ride.