A recently identified galactic filament, extending an impressive 50 million light-years and situated 140 million light-years distant, exhibits galaxies in orbital motion around its central axis. This arrangement positions it as one of the most substantial rotating cosmic structures uncovered to date.
A depiction illustrating the rotational patterns of neutral hydrogen (right) within galaxies embedded in an extensive filament (middle), where these galaxies display a unified bulk rotational movement that mirrors the grand cosmic web (left). Credit: Lyla Jung.
Cosmic filaments represent the Universe’s most expansive known formations: immense, thread-like arrangements of galaxies and dark matter that constitute a universal structural framework.
Furthermore, they function as conduits, facilitating the transport of matter and momentum into galaxies.
Adjacent filaments populated by numerous galaxies exhibiting synchronized rotation, and where the entire structure appears to be in a state of rotation, offer optimal environments for investigating the origins of galactic spin and the acquisition of gas observed today.
These systems also provide a means to validate theoretical models concerning the accumulation of cosmic rotation over timescales spanning tens of millions of light-years.
In a recent investigation led by Lyla Jung, an astronomer at the University of Oxford, along with her collaborators, 14 nearby hydrogen-rich galaxies were identified. These galaxies are arrayed in an elongated, linear configuration measuring approximately 5.5 million light-years in length and 117,000 light-years in width.
This particular arrangement is situated within a far more extensive cosmic filament, encompassing over 280 additional galaxies and spanning roughly 50 million light-years.
Significantly, a substantial proportion of these galaxies demonstrate rotational alignment with the filament itself, a pattern far exceeding what would be expected from random galaxy spins.
This finding challenges prevailing cosmological models, suggesting that large-scale cosmic structures might exert a more pronounced or prolonged influence on galactic rotation than previously hypothesized.
The research team observed that galaxies situated on opposing sides of the filament’s core are traversing in inverse directions, an indication that the entire structure is undergoing rotation.
Employing models that simulate filament dynamics, they deduced a rotational velocity of 110 km/s and estimated the radius of the filament’s densest central region to be approximately 163,000 light-years.
“The exceptional nature of this structure lies not only in its magnitude but also in the congruence of spin alignment and rotational motion,” stated Dr. Jung.
“One can draw an analogy to a theme park’s teacup ride. Each galaxy resembles a spinning teacup, while the entire platform – the cosmic filament – is also rotating.”
“This dual form of motion affords us an uncommon perspective on how galaxies acquire their angular momentum from the larger cosmic environments they inhabit.”
The filament appears to represent a nascent, relatively undisturbed cosmic entity.
Its high density of gas-rich galaxies and minimal internal movement – a state described as dynamically cold – suggest that it is still in an early phase of its evolution.
Given that hydrogen serves as the fundamental building block for star formation, galaxies abundant in hydrogen gas are actively accumulating or retaining the necessary fuel for stellar genesis.
Consequently, the examination of such galaxies provides valuable insights into the initial or ongoing phases of galactic development.
Hydrogen-rich galaxies also serve as excellent indicators of gas flow along cosmic filaments.
Due to the susceptibility of atomic hydrogen to motion-induced disturbances, its presence helps elucidate the pathways by which gas is channeled through filaments into galaxies, offering clues about the flow of angular momentum across the cosmic web and its impact on galactic shape, spin, and star formation.
“This filament acts as a preserved historical record of cosmic movements,” remarked Dr. Madalina Tudorache, an astronomer associated with the University of Cambridge and the University of Oxford.
“It aids us in reconstructing the processes by which galaxies gain their spin and evolve over time.”
The research utilized observational data acquired by South Africa’s MeerKAT radio telescope, one of the world’s leading astronomical instruments, comprising an intricate network of 64 interconnected satellite dishes.
The discovery of this rotating filament was facilitated by a comprehensive sky survey known as MIGHTEE.
This was integrated with optical observational data from the DESI and SDSS surveys, enabling the identification of a cosmic filament exhibiting both synchronized galaxy spin orientation and collective rotational movement.
“This genuinely underscores the efficacy of combining data streams from diverse observatories to achieve a more profound understanding of how grand cosmic structures and galaxies come into being within the Universe,” commented Professor Matt Jarvis of the University of Oxford.
The findings of this investigation are detailed in a publication featured in the journal Monthly Notices of the Royal Astronomical Society.
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Madalina N. Tudorache et al. 2025. A 15 Mpc rotating galaxy filament at redshift z = 0.032 Available for Purchase. MNRAS 544 (4): 4306-4316; doi: 10.1093/mnras/staf2005
