Cosmic or galactic filaments are the largest ‘threads’ in the cosmic web of the universe. A single cosmic filament is a structure spanning hundreds of millions of light years, formed as a result of gravity pulling gas, dark matter and galaxies into long, thin strings that connect vast clusters of galaxies. The filaments also occupy large, empty regions of space called voids.

A filament is formed where sheets of matter intersect and collapse; They are also highways along which gas and smaller galaxies ‘flow’ towards larger clusters. As material falls in, it can rotate both the filament and the galaxies underlying it. Because of this, filaments help determine where galaxies form, how fast they grow, and how much fresh gas they acquire over billions of years.

Astronomers map filaments by measuring the positions and distances of many galaxies and then tracing the patterns they form in the sky. Computer simulations have shown similar webs, leading astronomers to believe that these structures arose naturally from tiny ripples in the early universe and evolved under the influence of gravity into the vast, connected networks we see today. On December 3, researchers at the University of Oxford reported the detection of a filament about 50 million light-years long extended by at least 14 galaxies.

In particular, the team found that the way the galaxies were rotating while lining up along the filament suggested that the entire filament was rotating slowly. Thus the team claims that it is “one of the largest rotating structures ever found in the universe”.