A recently uncovered galactic filament measures at least 50 million light-years in length and is situated 140 million light-years away. A galaxy orbits around the filament’s core, making it one of the largest rotating structures found to date.
Illustration depicting the rotation (right) of neutral hydrogen in a galaxy situated within an elongated filament (center). The galaxies demonstrate coherent bulk rotational motion that traces a large-scale cosmic web (left). Image credit: Lyla John.
Cosmic filaments stand as the largest known structures in the universe, comprising extensive thread-like formations of galaxies and dark matter that serve as the framework of the cosmos.
They also function as “highways” through which matter and momentum funnel into galaxies.
A nearby filament, home to numerous galaxies spinning in the same direction, represents an excellent opportunity to investigate how galaxies developed their current spin and gas content.
This structural arrangement could also provide a basis to test theories regarding how the universe’s rotation accumulates over vast distances.
In a recent study, astronomer Lyra Jung and colleagues from the University of Oxford discovered that 14 nearby hydrogen-rich galaxies form a slender line stretching approximately 5.5 million light-years long and 117,000 light-years wide.
This alignment exists within a considerably larger cosmic filament, about 50 million light-years long, which encompasses over 280 additional galaxies.
Notably, many of these galaxies seem to rotate in the same direction as the filament itself, a pattern that exceeds what would be expected if their rotation were random.
This observation challenges existing models and implies that the universe’s structure may have a more potent and prolonged impact on galaxy rotation than was previously assumed.
Astronomers observed that galaxies flanking the filament’s core were moving in opposite directions, suggesting that the entire formation is in motion.
The team employed a model of filament mechanics to estimate a rotational speed of 110 km/s and calculated the radius of the filament’s dense core region to be about 163,000 light-years.
“What makes this structure remarkable is not just its size, but also the interplay of spin arrangement and rotational motion,” stated Dr. Jung.
“You can liken it to a teacup ride at a theme park. Each galaxy represents a spinning teacup, but the entire platform, the cosmic filament, is also in rotation.”
“This dual motion provides valuable insights into how galaxies acquire rotation from the larger structures they inhabit.”
The filaments appear to be relatively young and undisturbed.
The significant number of gas-rich galaxies, minimal internal motion, and their so-called dynamically cool state imply that the galaxy is still in its formative stages.
Hydrogen serves as the fundamental material for star formation, meaning that galaxies rich in hydrogen gas are actively gathering and retaining the necessary fuel to create stars.
Thus, exploring these galaxies could yield insights into both the early and ongoing phases of galaxy evolution.
Hydrogen-rich galaxies also serve as excellent indicators of gas flow along cosmic filaments.
Due to atomic hydrogen’s susceptibility to motion, its presence aids in mapping how gas is directed through filaments and into galaxies, shedding light on how angular momentum travels through the cosmic web and influences galaxy shape, rotation, and star formation.
“This filament serves as a fossil record of the universe’s flow,” remarked astronomer Dr. Madalina Tudrache from the Universities of Cambridge and Oxford.
“It helps us comprehend how galaxies gain rotation and evolve over time.”
The researchers used data from the MeerKAT radio telescope in South Africa, one of the most powerful telescopes globally, comprising an array of 64 linked satellite dishes.
This rotating filament was detected via an extensive sky survey known as MIGHTEE.
By integrating this data with optical observations from the DESI and SDSS surveys, the study revealed cosmic filaments displaying both spin alignment and bulk rotation in coherent galaxies.
Professor Matt Jarvis from the University of Oxford stated: “This highlights the ability to combine data from various observatories to achieve a deeper understanding of how vast structures and galaxies form in the Universe.”
The findings are detailed in the following article: paper in Royal Astronomical Society Monthly Notices.
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Madalina N. Tudrache and others. 2025. A 15 Mpc rotating galactic filament with redshift z = 0.032 is available for purchase. MNRAS 544 (4): 4306-4316; doi: 10.1093/mnras/staf2005
Source: www.sci.news
