A razor-thin cosmic filament discovered by University of Oxford researchers 140 million light-years from Earth is one of the largest rotating structures ever found, with implications for early galaxy formation.
A cosmic filament is an enormous structure composed of galaxies and dark matter, arranged into a narrow thread, which serves as a highway for matter and momentum to enter galaxies. The discovery of the filament, composed of 280 galaxies, was reported in a recent paper published in the Monthly Notices of the Royal Astronomical Society.
Cosmic Filament
Data for the filament came from the MIGHTEE deep sky survey conducted with South Africa’s MeerKAT radio telescope, led by Matt Jarvis, of the University of Oxford’s Department of Physics. Supplemental data came from the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey.
“This really demonstrates the power of combining data from different observatories to obtain greater insights into how large structures and galaxies form in the Universe,” Professor Jarvis explained. “Such studies can only be achieved by large groups with diverse skillsets, and in this case, it was really made possible by winning an ERC Advanced Grant/UKIR Frontiers Research Grant, which funded the co-lead authors.”
It was through the team’s analysis of individual galaxies’ spins that they began to suspect the entire filament was rotating. On either side of the filament’s spin, galaxies were spinning in opposite directions, which provided data to plug into existing filament dynamics models. From those models, the team calculated that the filament is rotating at 110 kilometers per second and that its dense center has a radius of roughly 163,000 light-years.
“What makes this structure exceptional is not just its size, but the combination of spin alignment and rotational motion,” said co-lead author Dr Lyla Jung of the University of Oxford’s Physics Department. “You can liken it to the teacups ride at a theme park. Each galaxy is like a spinning teacup, but the whole platform- the cosmic filament -is rotating too.”
“This dual motion gives us rare insight into how galaxies gain their spin from the larger structures they live in,” she added.
Exploring Galaxy Formation
When two filaments in close proximity rotate in the same direction, they provide a crucial opportunity for scientists to study how individual galaxies evolved to their present spin and gas content. Additionally, such tandem filaments allow researchers to test theories about the buildup of cosmic radiation over large distances spanning tens of millions of light-years.
The researchers were particularly interested in a group of 14 hydrogen-rich galaxies in a 5.5-million-light-year-long string that is only 117,000 light-years wide, which sits within the larger 50-million-light-year-long filament. Intriguingly, in this narrow string, a statistically significant number of those 14 galaxies are spinning in the same direction as the filament itself, suggesting a correlation. If true, this presents a considerable challenge to current theories, which do not allow for such strong or long-term influence from cosmic structures on galaxy rotation.
The filament appears quite young, making it an ideal laboratory for studying how galaxies evolve. On a large scale, the filament has low internal motion, a sign of early development. On the level of individual galaxies, they are mostly hydrogen-rich, full of raw star material. Such galaxies are typically young and undergoing heavy star formation.
As hydrogen gas flows into these hungry young galaxies, it provides researchers with a way to track the momentum that pushes those easily disturbed hydrogen atoms along the filament. In turn, the team can then identify how that momentum builds to impact the morphology, spin, and star formation of entire galaxies.
Continuing Work
The work may be helpful to future surveys planned for the European Space Agency’s Euclid Mission and the Vera C. Rubin Observatory. The intrinsic alignments of galaxies pose a major data-cleaning challenge for those projects. By studying this cosmic filament, researchers will be able to gain a better grasp of those alignments and develop models to understand future survey data.
As researchers continue to explore the cosmos, modern advanced observation platforms are recording previously unseen early developmental states of stars, galaxies, and the universe as a whole. These new observations, such as those from the James Webb Space Telescope, are challenging current models, leading to debate and reappraisal as an expanding cosmic record provides new insights into how our universe and its features evolve.
“This filament is a fossil record of cosmic flows,” said co-lead author Dr Madalina Tudorache of the University of Cambridge’s Institute of Astronomy and the University of Oxford’s Department of Physics. “It helps us piece together how galaxies acquire their spin and grow over time.”
The paper, “A 15 Mpc Rotating Galaxy Filament at Redshift 𝑧 = 0.032,” appeared in Monthly Notices of the Royal Astronomical Society on December 4, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.