Cosmic filaments may be the biggest spinning objects in space

Cosmic filaments may be the biggest spinning objects in space

Understanding the rotation of filaments might help astronomers determine the origins of cosmic spin.

Moons, stars, and even entire galaxies do it. Now, two teams of scientists claim that cosmic filaments do it as well. These tendrils stretch hundreds of millions of light-years spin, twirling like giant corkscrews.

Cosmic filaments are the universe’s greatest known structures, containing the bulk of its mass. The cosmic web is connected by these dense, skinny strands of dark matter and galaxies, which guide matter toward galaxy clusters at each strand’s end.

Matter did not rotate at the Big Bang, but it began to spin when stars and galaxies formed. Until recently, galaxy clusters were the biggest rotating formations known. “Conventional thinking on the subject said that’s where spin ends. You can’t really generate torques on larger scales,” says Noam Libeskind, cosmologist at the Leibniz Institute for Astrophysics Potsdam in Germany.

Cosmic filaments are strands of dark matter and galaxies that rotate (illustrated). As the filaments spin, they pull matter into their orbit and toward galaxy clusters at each end. A. KHALATYAN/J. FOHLMEISTER/AIP

So the fact that filaments spin — at a scale that reduces galaxies to dust particles — is perplexing. “We don’t have a full theory of how every galaxy comes to rotate, or every filament comes to rotate,” says Mark Neyrinck, cosmologist at the University of the Basque Country in Bilbao, Spain.

Neyrinck and colleagues used a 3-D cosmological simulation to assess the velocities of dark matter clumps as they travelled along a filament to test for rotation. He and his colleagues detail their findings in a publication published in the Monthly Notices of the Royal Astronomical Society. Meanwhile, Libeskind and colleagues looked for rotation in the real universe, as reported in Nature Astronomy. The scientists used the Sloan Digital Sky Survey to map galaxies’ motions and quantify velocities perpendicular to filament axes.

A computer simulation depicts how a cosmic filament twists galaxies and dark matter into a cosmic web strand. Filaments pull matter into rotation and into clusters at their ends, which are shown here by “test particles” shaped like comets.

Despite using different approaches, the two teams discovered similar rotational velocities for filaments, which Neyrinck describes as a “encouraging [indication] that we’re looking at the same thing.”

Next, researchers seek to figure out what causes these massive space constructions to rotate and how they get started. “What is that process?” Libeskind says. “Can we figure it out?”

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Sören Backman
Sören Backman
6 months ago

Forget about “dark matter”. These ropes are called Birkeland currents and are guided by electric and magnetic fields and forces.

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