Huge rotating structure of galaxies and dark matter is detected

By Will Dunham

WASHINGTON, Dec 8 (Reuters) – Scientists have observed the largest known spinning structure in the cosmos: a gargantuan threadlike collection of hundreds of galaxies, gas and dark matter that forms a filament in the macrostructure of the universe called the cosmic web.

The filament, located about 140 million light-years from Earth, has been observed by scientists primarily using the MeerKAT radio telescope in South Africa, an array of 64 interconnected parabolic antennas.

The spinning filament is surprisingly large, measuring about 50 million light-years long and 117,000 light-years wide. A light year is the distance light travels in a year, or 5.9 trillion miles (9.5 trillion km). ‌For comparison, our galaxy, the Milky Way, which itself is part of a filament of the cosmic web, is approximately 100,000 light years across.

“We think that the very large-scale universe is made up of a network distribution of galaxies, gas and dark matter,” said Madalina Tudorache, an astrophysicist at the University of Cambridge, co-lead author of the study published this month in the journal Monthly Notices of the Royal Astronomical Society.

“This network is called the cosmic web, and it is made up of clusters, which are very dense clumps of matter, often formed from multiple groups of galaxies; voids, which are empty or nearly empty regions of space; and filaments, which are strand-like structures that connect very dense regions and border the voids,” Tudorache said.

The rotating filament described in the new study is populated by nearly 300 galaxies of varying sizes as well as gas and dark matter, the mysterious invisible substance that is estimated to make up 27% of the cosmos.

Everything visible in the universe is ordinary matter: stars, planets, moons, and everything on Earth. It can be observed in wavelengths from infrared to visible light and gamma rays, but only makes up about 5% of the universe. Dark matter, on the other hand, does not absorb, reflect or emit light, but its presence is known thanks to its large-scale gravitational effects.

Researchers determined that the filament rotates by observing that galaxies on either side of its central axis move through space in opposite directions, all having a rotational speed of about 246,000 miles (396,000 km) per hour.

“This is the largest individual rotating structure detected so far. Statistically, we believe there are other rotating structures, some of which might be larger. However, we have not been able to detect them directly with our current data and telescopes,” said Lyla Jung, an astrophysicist at the University of Oxford and co-lead author of the study.

The researchers compared what they see in this filament to an amusement park attraction called the Teacup Ride.

“The analogy between the teacup and the ride explains the two levels of rotational motion that make this object unique,” ​​Jung said.

“First, each galaxy in the filament rotates on its own. The gas and stars in each galaxy orbit the center of the galaxy, like each teacup on the merry-go-round, rotates individually. Second, the entire cosmic filament also rotates. The filament is made up of many galaxies, and this study demonstrates that the entire structure rotates, like the teacup platform rotates as a whole,” Jung added.

In studying the cosmos, astrophysicists examine it on the smallest and largest scales. They examine tiny fundamental particles such as neutrinos. They observe objects such as comets, asteroids, moons, planets and stars that make up solar systems. They observe galaxies made up of billions of stars and galaxy clusters. And then, on a larger scale, they examine the filaments and other components of the cosmic web.

This study looks at the big end of things.

“This is a very exciting time to be working in this field, as our ability to discover such structures increases with the advent of better radio and optical studies. This will deepen our understanding of the universe,” said Tudorache.

(Reporting by Will Dunham; editing by Daniel Wallis)