Key Takeaways:
- These giant structures, millions of light-years long, rotate like giant corkscrews.
- They contain most of the universe’s mass and connect galaxy clusters.
- Until recently, galaxies were thought to be the largest spinning structures.
- Scientists don’t fully understand how these massive filaments acquired their rotation.
- Research is ongoing to understand what causes filaments to spin and how it began.
Moons do it. Stars do it. Even entire galaxies do it. Now, two teams of scientists claim that the universe’s largest known structures do as well. Cosmic filaments spin. These massive threads extend hundreds of millions of light-years into space and twirl like giant corkscrews.
Cosmic filaments are dense, thin filaments of dark matter and galaxies. They hold the majority of the universe’s mass. You can think of filaments as the threads connecting the cosmic web. Filaments twist, pulling matter in and toward galaxy clusters at the ends of each strand.
The Big Bang is the explosion of matter that created our universe. At that point, matter did not rotate. Then, as stars and galaxies formed, they started spinning. Until recently, galaxy clusters were the largest structures known to rotate.
Noam Libeskind is a cosmologist at the Leibniz Institute for Astrophysics in Potsdam, Germany. “Conventional thinking on the subject said that’s where spin ends,” according to him. Torques are the forces that cause spins. “You can’t really generate torques on larger scales,” he says.
Filaments are so large that galaxies appear to be specks of dust. So it’s a puzzle to discover that filaments spin. “We don’t have a full theory of how every galaxy comes to rotate, or every filament comes to rotate,” says Mark Neyrinck. He is a cosmologist at the University of the Basque Country. That is in Bilbao, Spain.
Neyrinck and his colleagues discovered that filaments can rotate by using a 3-D computer model of the universe. They used it to calculate the velocities of dark matter clumps moving around a filament.
Meanwhile, Libeskind and his colleagues looked for rotation in the physical universe. The team mapped galaxies’ motions. The researchers then measured the velocities of galaxies perpendicular to the center of a filament.
Although the two teams searched for spin in different ways, they discovered similar signs of rotational velocity. That’s “encouraging,” Neyrinck says. It implies “that we’re looking at the same thing.”
Next, researchers want to figure out what causes these massive space structures to spin and how their enormous rotation began. “What is that process?” Libeskind explains. “Can we figure it out?”
A computer simulation shows how a cosmic filament twists galaxies and dark matter as it spins. Filaments pull matter into rotation and toward clusters at their ends, visualized here with “test particles” shaped like comets.
