This Might Be the Biggest Thing in the Universe That Spins

Astronomers suspect that the universe’s backbone is an enormous web of thread-like structures known as filaments. Turns out filaments also spin—like, really fast, on scales of tens of millions of light-years.

This enormous, spinning cosmic filament is roughly 50 million light-years long and contains nearly 300 galaxies. These embedded galaxies appear to spin in the same direction as the filament itself—suggesting that cosmic “background†structures exert far more influence on galaxies than was previously believed. A study published on December 3 in Monthly Notices of the Royal Astronomical Society describes the findings in greater detail.

“You can liken it to the teacups ride at a theme park,†Lyla Jung, an astrophysicist at the University of Oxford, said in a statement. “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.â€

Cosmic spiderwebs

Cosmological models suggest that the early universe was very smooth. But over time, small densities of cosmic dust and dark matter bunched together in different places, growing into web-like patterns. It was from these cosmic filaments that stars and galaxies as we know them today emerged.

This is still true today, with cosmic filaments serving as “highways†for matter and momentum to flow into galaxies, the researchers explained in the release. But astronomers weren’t completely certain about the extent to which these filaments affected the spin and gas of galaxies—the exact metrics scientists use to investigate the key characteristics of galaxies, such as their evolution over astronomical time.

In that sense, cosmic filaments, as the backbone structure of these galaxies, are akin to “a fossil record of cosmic flows,†added Madalina Tudorache, study co-author and an astrophysicist at Oxford, in the release. “It helps us piece together how galaxies acquire their spin and grow over time.â€

Stringing together cosmic data

For the discovery, the researchers used a combination of data from the MeerKAT radio telescope, DESI, and the Sloan Digital Sky Survey. Specifically, they focused on the hydrogen content of 14 galaxies sitting inside a 5.5 million light-year-long section of the larger filament.

“Because atomic hydrogen is more easily disturbed by motion, its presence helps reveal how gas is funnelled through filaments into galaxies,†explained the researchers. This could offer important clues about how the momentum of the larger filament transfers to young galaxies, they added.

The galaxies on the far end of the filament section rotated in opposite directions, hinting to the researchers that the entire structure was rotating. The team then applied existing models to calculate the motion of the filament. Their analysis suggested that the filament itself was a young, “relatively undisturbed†structure in its early stages.

The universal web

Most surprisingly, they saw that the spin alignment of the galaxies and the filament was “significantly stronger than predicted by simulations or found in previous observations,†according to the study. If such strong alignments are typical for the universe, underaccounting for the role of filaments could introduce errors into astronomical observations, the paper noted.

The new findings truly speak to how closely connected everything is in the universe. That arguably makes studying things much more difficult—so many things to consider!—but it’s fascinating to see and anticipate how each connection will help answer questions about the universe.