The largest spinning objects in the universe are filled with galaxies, and the finding hints that things in the cosmos may be far more dynamically connected than previously imagined.
A FILAMENT FILLED WITH GALAXIES MOVING IN HELICAL MOTION.
IMAGE: AIP/ A KHALATYAN/ J FOHLMEISTER
From our tiny human perspective on Earth, the universe can seem like a deceptively stable place. But in reality, our planet is a rotating orb located in a solar system that sweeps around the center of the Milky Way, which is itself just one of billions of spinning galaxies across the observable universe.
It seems that no matter where we look, objects in the universe are dizzily spinning away. Now, scientists led by Peng Wang, a postdoctoral researcher at Leibniz Institute for Astrophysics Potsdam (AIP), have discovered that objects can rotate on previously unheard-of scales that span hundreds of millions of light years.
The mind-boggling finding reveals that filaments within the cosmic web, an enormous network of dark matter and gas structures that connects the universe, are rotating, making them “the largest objects known to have angular momentum,” according to a study published on Monday in Nature Astronomy.
“It's a major finding,” said Noam Libeskind, a cosmologist at AIP who initiated the project and co-authored the study, in a joint call with Wang. “It's a pretty big deal that we've discovered angular momentum, or vorticity, on such a huge scale.”
“I think it will help people understand cosmic flows and how galaxies are moving throughout the cosmic web and through the universe,” he added. “It will help us better understand the important scales for galaxy formation and ultimately, why everything in the universe is spinning and how spin is generated. That is a really, really hard question to solve. It's an unsolved question in cosmology.”
It’s difficult to even contemplate the scales of the spinning filaments, which are threads primarily made of dark matter, a mysterious unidentified substance that is common in the universe. These structures connect distant galaxy clusters and contain gas streams and populations of galaxies within their gargantuan tubular extents. It’s clear that filaments influence the motions of galaxies inside of them to some degree, but the movements of the intergalactic structures themselves, and their exact effect on galactic dynamics, have remained elusive for years.
“There's some order in this chaotic universe.”
Wang and his colleagues set out to investigate this problem by meticulously examining hundreds of thousands of galaxies within a few billion light years of Earth captured by the Sloan Digital Sky survey based in New Mexico.
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“If the internal rotation of the galaxies themselves is consistent with the filament rotation—if the filament rotation is actually endowing galaxies with their spin—that would be an absolutely fascinating connection,” Libeskind said. “To actually see it in real observations, to see that galaxies are spinning with the filament, would help us understand how gas collapses to form galaxies.”
Scientists, including the authors of the new paper, have widely speculated about this possible connection between the motions of galaxies and the wider cosmic web. In some cases, galaxies that are located tens of millions of light years away seem to be rotationally synced up with each other, suggesting that they are influenced by the same large-scale structures.
However, Wang’s team is the first to actually measure the rotation of one of these structures, bringing the topic from hypothetical discussion into an observational reality. The new study not only smashes the record for measuring spin on such unprecedented scales, it also hints that objects in the universe may be far more dynamically connected—even across vast distances—than previously imagined.
“For me, at least, it’s incredibly inspiring to know that there's some sort of cosmos to the chaos,” Libeskind said. “There's some order in this chaotic universe. It's really mesmerizing to find these patterns, to look at the heavens and to look at these galaxies that are, on these scales, just specks of dust, and to say: ‘Wow, they're not just swarming randomly. There's actually an ordered motion to them. They're actually moving. They all know about each other. They're all feeling the same gravitational field. They're all moving in the same way.’”
“I'm awed by it every day of my life,” he concluded.
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