Scientists Finds Galaxies Rotating Together Inside Massive Dark Matter Thread

The universe has revealed a surprising pattern as a group of galaxies inside a huge dark matter filament has been found rotating in the same direction as the filament itself. This unusual finding challenges what scientists believed about how a galaxy's surroundings shape its growth and evolution, reported Space.com.

The filament is a part of the vast cosmic web composed primarily of dark matter and interspersed with lighter layers of normal matter. Located approximately 140 million light-years from Earth, its structure appears to be layered. 

At its center, 14 galaxies are arranged almost perfectly in a straight line, spanning approximately 5.5 million light-years in length and 117,000 light-years in width. These galaxies contain an abundance of hydrogen gas, essential for star formation.

This line of galaxies is part of a larger filament, approximately 50 million light-years in length and containing approximately 300 galaxies. 

This group is considered unique because it is not simply arranged in a narrow line, but many of these galaxies rotate in the same direction as the entire filament. 

Each galaxy slowly rotates on its axis while also orbiting a larger rotating structure. These galaxies are aligned perpendicular to the long axis of the filament and rotate around it at a speed of 68 miles per second, or 110 kilometers, in the same direction as their own rotation. 

Together, they form one of the largest known collectively rotating structures in the universe.

Researchers said this discovery is significant not only because of its size, but also because the galaxies' spin and their combined motion appear to be consistent. Laila Jung of Oxford University explained that it resembles a teacup ride at a theme park, where each cup rotates independently and the entire platform rotates simultaneously. This helps explain how galaxies can derive their spin from the larger cosmic structure.

The study was led by Laila Jung and Madalina Tudorache of Oxford. They used the MeerKAT radio telescope in South Africa, which has 64 connected dishes. They measured the speeds of the galaxies and the neutral hydrogen gas in the filament. They also incorporated optical data from the Dark Energy Spectroscopic Instrument at Kitt Peak National Observatory in Arizona and the Sloan Digital Sky Survey in New Mexico.

In 2022, scientists discovered that cosmic filaments rotate based on the motions of their internal galaxies. The new discovery shows that galaxies are also rotating in the same direction as the entire filament, which is quite unexpected. Scientists have long believed that a galaxy's spin comes from the rotation of the gas from which it formed billions of years ago. Over time, collisions and other nearby galaxies can alter this spin.

But in this case, the filament's influence is very clear. It is believed that the filament transports hydrogen gas along its dark matter structure to galaxies, affecting their spin and providing material for the formation of new stars. Tudorache described this filament as a fossil record of cosmic flow, helping to understand how galaxies acquire their spin and evolution. 

The galaxies in this filament appear to be young and in their early stages, so their spins may change in the future. Nevertheless, the filament's large impact is surprising and may require changes to existing theories of galaxy formation.

This discovery could impact weak lensing surveys, including the Legacy Survey of Space and Time at the Vera C Rubin Observatory in Chile. 

These surveys study subtle changes in galaxy shape caused by dark matter to understand the structure of the cosmic web. A better understanding of how galaxies align and rotate along the filament will allow for more precise measurements.

The discovery of this alignment of galaxies in this rotating filament was published on December 4 in the journal Monthly Notices of the Royal Astronomical Society.