A massive galaxy from less than 2 billion years after the Big Bang is baffling astronomers because it shows no sign of rotation.
Astronomers using the James Webb Space Telescope have identified an unusual galaxy from the early universe that appears to be missing something scientists expected to find: rotation.
Researchers say galaxies are generally thought to begin spinning as they form, driven by gravity and streams of inflowing gas. But this distant galaxy, known as XMM-VID1-2075, does not show signs of that motion, making it an unexpected discovery.
The finding was described in a study published May 4 in Nature Astronomy. Lead author Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis, said galaxies without noticeable rotation are usually only seen much later in cosmic history.
“This one in particular did not show any evidence of rotation, which was surprising and very interesting,” Forrest said.
Early Universe Galaxy Challenges Expectations
Current models of galaxy formation suggest that young galaxies should naturally spin as they gather matter. Over billions of years, however, repeated mergers between galaxies can disrupt or partially cancel that motion.
That process is believed to take an extremely long time. Because of this, astronomers were surprised to find a galaxy with these characteristics when the universe was still less than 2 billion years old.
Nearby massive galaxies sometimes show little organized rotation and instead contain stars moving in many random directions. Scientists typically associate that behavior with galaxies that have undergone long histories of collisions and mergers.
Massive Ancient Galaxy Already Stopped Forming Stars
Before using Webb, Forrest and his colleagues in the MAGAZ3NE (Massive Ancient Galaxies at z>3 NEar-Infrared) survey had already observed XMM-VID1-2075 with the W.M. Keck Observatory in Hawaiʻi.
Those earlier observations revealed that the galaxy was already enormous for its time, containing several times as many stars as the Milky Way. The data also showed that the galaxy had largely stopped producing new stars.
“Previous MAGAZ3NE observations had confirmed this was one of the most massive galaxies in the early universe, with already several times as many stars as our Milky Way, and also confirmed that it was no longer forming new stars, making it a compelling target for follow-up observations,” Forrest said.
James Webb Measures Galaxy Motion
The research team later used the James Webb Space Telescope to study XMM-VID1-2075 and two other galaxies from roughly the same era in greater detail. Webb allowed the astronomers to measure how material was moving within each galaxy.
“This type of work has been done a lot with nearby galaxies because they’re closer and larger and so you can do these kinds of studies from the ground, but it’s very difficult to do with high redshift galaxies because they appear a lot smaller in the sky,” Forrest said. “(James Webb Space Telescope) is really pushing the frontier for these kinds of studies.”
Among the three galaxies examined, one showed clear rotation, another appeared more irregular, and XMM-VID1-2075 displayed random motion without overall spin.
“That’s consistent with some of the most massive galaxies in the local universe, but it was a bit surprising to find it so early on,” Forrest said.
Possible Ancient Galaxy Collision
Astronomers are now trying to determine how this galaxy became what scientists describe as a “slow rotator” so quickly.
One explanation is that the galaxy may have experienced a major collision with another galaxy spinning in nearly the opposite direction. Such an event could have disrupted or canceled much of the system’s rotation.
Researchers believe Webb’s observations may support that idea.
“For this particular galaxy, we see a large excess of light off to the side. And so that’s suggestive of some other object which has come in and is interacting with the system and potentially changing its dynamics,” Forrest said.
Searching for More Non-Rotating Galaxies
The team plans to continue searching for other galaxies like XMM-VID1-2075 in the early universe. Scientists can then compare those discoveries with computer simulations to better understand how galaxies evolved shortly after the Big Bang.
“There are some simulations that predict that there will be a very small number of these non-rotating galaxies very early in the universe, but they expect them to be quite rare. And so this is one way in which we can test these simulations and really figure out how common they are, and that can then give us information about whether our theories of this evolution are correct,” Forrest said.
Reference: “A massive and evolved slow-rotating galaxy in the early Universe” by Ben Forrest, Adam Muzzin, Danilo Marchesini, Richard Pan, Nehir Ozden, Jacqueline Antwi-Danso, Wenjun Chang, M. C. Cooper, Adit H. Edward, Percy Gomez, Lucas Kimmig, Brian C. Lemaux, Ian McConachie, Allison Noble, Rhea-Silvia Remus, Stephanie M. Urbano Stawinski, Gillian Wilson and M. E. Wisz, 4 May 2026, Nature Astronomy.
DOI: 10.1038/s41550-026-02855-0
Additional coauthors on the paper are: Brian C. Lemaux, UC Davis and Gemini Observatory, Hawaiʻi; Adam Muzzin and Adit H. Edward, York University, Toronto; Danilo Marchesini, Richard Pan and Nehir Ozden, Tufts University; Jacqueline Antwi-Danso, University of Toronto; Wenjun Chang, UC Riverside; M. C. Cooper and Stephanie M. Urbano Stawinski, UC Irvine; Percy Gomez, W. M. Keck Observatory, Kamuela, Hawaiʻi; Lucas Kimmig and Rhea-Silvia Remus, Ludwig-Maximilians-Universität München, Germany; Ian McConachie, University of Wisconsin-Madison; Allison Noble, Arizona State University; and Gillian Wilson and M. E. Wisz, UC Merced.
The study was supported by grants from NASA, the Space Telescope Science Institute, and the National Science Foundation.
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