More Theory-Changing Old Galaxies

by | December 6, 2023, 8:00 PM | Galaxies & Cosmology

Credit: Cluster image: NASA, UNCOVER (Bezanson et al., DIO: 10.48550/arXiv.2212.04026). Insets: Nasa, UNCOVER (Wang et al., 2023); Composition: Dani Zemba/Penn State

Ok, I have to admit, the JWST is finding objects so exceedingly weird that my first reaction is to say. “Imma wait until that is confirmed by someone else, because… how?”

Case in point: In April, the JWST Advanced Deep Extragalactic Survey released a paper saying they had found galaxies in JWST images that appeared to be shining from when the universe was a few hundred million years old.  We talked about this story but made it clear future data could move those galaxies a bit closer to us in time. At least one of those galaxies we now know is closer, but others are confirmed to be just that far away.

Now, another collaboration, the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization team, or the UNCOVER team, has looked at another region with the JWST and also found galaxies from when the Universe was a few hundred million years old. 

Folks, our Universe made galaxies faster than any professor or researcher paper ever led me to anticipate. How did this happen? No idea, but it is super cool to see.

To see objects this far away in time and space, researchers had to combine the light-gathering power of the JWST with the light-magnifying power of massive galaxy clusters. The UNCOVER team used the Pandora cluster, which is located about four billion light years away toward the constellation Sculptor. 

Images by JWST, released in February, allowed the team to find 60,000 light sources that might be shining from the early universe, and follow-up observations of the best 700 are underway. 

A new paper in the Astrophysical Journal Letters, led by Bingjie Wang, uses the gold standard technique of spectroscopy to show two of these galaxies are shining from when the universe was just 330 million years old. Ranked as the second and sixth oldest known galaxies, they are also the largest systems so far seen, which admittedly still doesn’t make them all that big. One appears to be about 2000 light-years across, which makes it 5000 times smaller than our Milky Way but viewed in perspective, it’s huge. 

According to Wang, “Previously discovered galaxies at these distances are point sources — they appear as a dot in our images. But one of ours appears elongated, almost like a peanut, and the other looks like a fluffy ball.”

These galaxies also have outsized brightnesses because they are full of massive young stars and star formation. They have remarkably few heavy elements in them, as well. Team member Joel Leja explains, “The first elements were forged in the cores of early stars through the process of fusion.  It makes sense that these early galaxies don’t have heavy elements like metals because they were some of the first factories to build those heavy elements.”

Before JWST, astronomers couldn’t see this region of space-time in any detail, and we’re now learning all the things we assumed would be happening are indeed happening… just earlier than we dreamed. Our theories got the big picture right, and over time, scientists will work out the details.