In the vastness of today’s universe, galaxies predominantly exhibit ordered rotation. However, among the largest star systems, those that do not form new stars are often influenced by chaotic stellar motion. Astronomers refer to these galaxies as slow-rotators. While fast-rotating systems are frequently observed, slow-rotators are believed to be rare, especially in the early universe. Recent findings from the NASA/ESA/CSA James Webb Space Telescope have illuminated a slowly rotating giant galaxy known as XMM-VID1-2075, located at redshift z = 3.449, which means we are observing a galaxy that is approximately 12 billion years old.
The Webb/NIRSpec/IFU image depicting the slowly rotating galaxy XMM-VID1-2075. Credit: Forest et al., doi: 10.1038/s41550-026-02855-0.
Current astronomical theories indicate that the first galaxies formed through the acquisition of angular momentum from inflowing gas, coupled with gravitational forces causing them to rotate.
Over billions of years, many galaxies—particularly those within clusters—undergo numerous mergers. These interactions lead to their combined rotations either enhancing or partially countering each other.
This phenomenon explains why some galaxies nearest to Earth display minimal overall rotation, yet contain considerable random stellar movement.
The discovery of XMM-VID1-2075 as a slow rotator is surprising, especially considering it reached this state when the universe was less than 2 billion years old.
“This invariant characteristic can typically only be observed in the most massive, mature galaxies closer to us in space and time,” stated Ben Forrest, an astronomer from the University of California, Davis.
“It was particularly striking that we found this galaxy exhibiting no indications of rotation, which raises intriguing questions.”
Ben Forrest and his team, part of the MAGAZ3NE (z>3 NEar-Infrared Giant Ancient Galaxies) survey, had previously conducted observations of XMM-VID1-2075 at the WM Keck Observatory in Hawaii.
“Earlier MAGAZ3NE observations confirmed that this galaxy ranks among the most massive in the early universe, possessing several times the number of stars as the Milky Way and not forming any new stars, making it an exceptional candidate for further study,” Dr. Forrest added.
Astronomers utilized the NASA/ESA/CSA James Webb Space Telescope to evaluate the relative motion of matter within XMM-VID1-2075, along with two other similarly aged galaxies.
“Conducting this type of analysis is standard for nearby galaxies due to their proximity and size, allowing for ground-based studies. Nevertheless, it’s challenging with high-redshift galaxies since they appear much smaller from our vantage point,” Dr. Forrest explained.
“The Webb Telescope is pioneering new research frontiers in this field.”
“Among the three galaxies we examined, one displayed clear rotation, one exhibited a somewhat chaotic pattern, while one showed no rotation but random stellar movement.”
“This pattern aligns with the characteristics of some of the most massive galaxies in our local universe, yet the early discovery of this slow rotator is quite unexpected.”
What led to the formation of this slow-rotating galaxy in under 2 billion years?
One hypothesis is that XMM-VID1-2075’s slow rotation may not stem from multiple mergers, but rather a singular collision between two galaxies rotating in nearly opposite directions, a notion supported by the team’s observations.
“In this galaxy, we observe a significant excess of light on one side,” Dr. Forrest noted.
“This suggests that an additional entity may be interacting with the system, potentially altering its dynamics.”
This groundbreaking research is detailed in the following paper published in Nature Astronomy.
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B. Forrest et al.. Discovery of a massive, slowly rotating galaxy from the early universe. Nat Astron, published online May 4, 2026. doi: 10.1038/s41550-026-02855-0
Source: www.sci.news
