The newly discovered filament of the galaxy spans at least 50 million light-years and is 140 million light-years away. Galaxies orbit around the filament's spine, making this spinning structure one of the largest yet discovered.
Figure illustrating the rotation of neutral hydrogen (right) in galaxies located in an elongated filament (center), where the galaxies exhibit coherent volumetric rotational motion that follows the large-scale cosmic web (left). Image credit: Laila Jung.
Cosmic filaments are the largest known structures in the Universe: huge filament-like formations of galaxies and dark matter that form cosmic forests.
They also act as “highways” through which matter and momentum flow into galaxies.
Nearby filaments containing many galaxies spinning in the same direction (and where the entire structure appears to spin) are ideal systems for studying how galaxies acquired the spin and gas they have today.
They could also provide an opportunity to test theories about how cosmic rotation forms over tens of millions of light years.
In a new study, Oxford University astronomer Laila Young and colleagues discovered 14 nearby hydrogen-rich galaxies arranged in a thin, elongated line about 5.5 million light-years long and 117,000 light-years wide.
This structure lies within a much larger cosmic filament containing more than 280 other galaxies and is approximately 50 million light years long.
Remarkably, many of these galaxies appear to rotate in the same direction as the filament itself—much more strongly than if the galaxies' rotation patterns were random.
This challenges current models and suggests that cosmic structures may influence the rotation of galaxies more strongly or for longer than previously thought.
Astronomers found that galaxies on either side of the filament's ridge were moving in opposite directions, suggesting that the entire structure was rotating.
Using models of the filament's dynamics, they determined the rotation speed to be 110 km/s and estimated the radius of the filament's dense central region to be approximately 163,000 light-years.
“What makes this structure exceptional is not only its size, but also the combination of rotational alignment and rotational motion,” Dr. Jung said.
“You can compare it to a teacup ride at a theme park. Each galaxy is like a spinning teacup, but the whole platform – the cosmic thread – is spinning too.”
“This double motion gives us rare insight into how galaxies receive rotation from the larger structures in which they live.”
The thread appears to be a young, relatively undisturbed structure.
The large number of gas-rich galaxies and low internal motion (the so-called dynamically cold state) suggest that it is still in an early stage of development.
Because hydrogen is the raw material for star formation, galaxies containing a lot of hydrogen gas actively collect or store fuel for star formation.
Thus, studying these galaxies can provide insight into the early or current stages of galaxy evolution.
Hydrogen-rich galaxies are also excellent indicators of the movement of gas along cosmic filaments.
Because atomic hydrogen is more easily disrupted by motion, its presence helps understand how gas is channeled through filaments into galaxies, offering clues to how angular momentum flows through the cosmic web, influencing galaxy morphology, rotation and star formation.
“This thread represents a fossilized record of cosmic flows,” said Dr Madalina Tudoras, an astronomer at the Universities of Cambridge and Oxford.
“This helps us understand how galaxies acquire their rotation and grow over time.”
The researchers used data from South Africa's MeerKAT radio telescope, one of the most powerful telescopes in the world, consisting of 64 interconnected satellite dishes.
This spinning filament was discovered by a deep sky survey called MIGHTEE.
Combined with optical observations from the DESI and SDSS surveys, a cosmic filament was discovered exhibiting both coherent galaxy spin alignment and bulk rotation.
“This really demonstrates the power of combining data from different observatories to gain a deeper understanding of how large structures and galaxies form in the Universe,” said Oxford University professor Matt Jarvis.
The discovery is reported in paper V Monthly Notices of the Royal Astronomical Society.
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Madalina N. Tudorace etc.. 2025. A rotating galaxy with a mass of 15 Mpc and a redshift of z = 0.032 is available for purchase. MNRAS 544(4):4306-4316; doi: 10.1093/mnras/staf2005
