Moons, stars, and even entire galaxies do it. Now, two teams of scientists claim that cosmic filaments do it as well. These hundreds of millions of light-year-long tendrils twist like enormous corkscrews.
Cosmic filaments are the universe’s greatest known formations, containing the majority of its mass. These dense, narrow threads of dark matter and galaxies connect the cosmic web, channeling matter to galaxy clusters at the ends of each strand.
Matter did not rotate at the Big Bang, but it began to spin as stars and galaxies formed. Until now, galaxy clusters were the biggest rotating formations known. “Conventional wisdom on the matter held that that was the end of spin. On higher scales, you can’t truly make torques,” says Noam Libeskind, cosmologist at Germany’s Leibniz Institute for Astrophysics Potsdam.
So the fact that filaments spin — at a scale that reduces galaxies to dust particles — is perplexing. “We don’t have a complete idea of how every galaxy or filament came to rotate,” says Mark Neyrinck, a cosmologist at the University of the Basque Country in Bilbao, Spain.
Neyrinck and colleagues utilized 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 in 2020 and now in press. 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 trace galaxies’ movements and quantify velocities perpendicular to filament axes.
Cosmic filaments are the universe’s greatest known formations, containing the majority of its mass. These dense, narrow threads of dark matter and galaxies connect the cosmic web, channeling matter to galaxy clusters at the ends of each strand. We don’t have a complete idea of how every galaxy or filament came to rotate.
Mark Neyrinck
Despite using different methodologies, the two teams discovered similar rotational velocities for filaments, which Neyrinck describes as an “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 exactly is that procedure?” According to Libeskind. “Are we going to find it out?”
The Hercules-Corona Borealis Great Wall is a supercluster of galaxies that astronomers have identified as the universe’s largest single structure. It is so large that light takes around 10 billion years to get across it. To put things in perspective, the cosmos is only 13.8 billion years old.
Space is all about large distances and objects. Earth is big to us, about 24,901 miles (40,075 kilometers) in circumference at the equator. But based on the cosmic scheme of things, Earth is tiny. Even in our own solar system, we are easily dwarfed by the planet Jupiter (which could fit more than 1,300 Earths inside) and our sun (which could fit more than a million Earths inside of it).
And, while our sun appears to be enormous, it pales in comparison to the largest stars known to us. The sun is a G-type star, also known as a yellow dwarf, and is fairly small on the cosmic scale. Some “hypergiant” stars are significantly larger than others. UY Scuti, the largest known star, could house more than 1,700 of our suns. (Some estimations place UY Scuti lower on the list, although there are other massive stars of a comparable size.) While UY Scuti is gigantic in diameter and circumference, it is only roughly 30 times the mass of our sun: volume and mass do not often correlate in space.
Even more large objects to contemplate are black holes, particularly supermassive black holes found in the center of galaxies. The Milky Way, for example, is home to one that is almost 4 million times the mass of the sun. NGC 4889 is home to one of the largest supermassive black holes ever discovered, with 21 billion times the mass of the sun. Even the most gigantic black holes, however, are not exceptionally large, because this form of structure is the densest in the universe.
Nebulas, or massive clouds of gas that frequently condense to become new stars, can also be quite large. NGC 604 in the Triangulum Galaxy is often regarded as one of the largest, measuring around 1,520 light-years across.
Galaxies are groupings of star systems and everything contained inside them, including black holes, planets, stars, asteroids, comets, gas, dust, and other objects. If we take our own Milky Way as a single object, it is around 100,000 light-years across. Scientists struggle to classify the largest galaxies because they lack definite boundaries; yet, the largest galaxies known to humanity are millions of light-years across.
