Cosmically huge (Image: R. G. Clowes/UCLan)
Largest structure challenges Einstein’s smooth cosmos
17:46 11 January 2013 by Jacob Aron
A collection of galaxies that is a whopping four billion light years long is the biggest cosmic structure ever seen. The group is roughly one-twentieth the diameter of the observable universe – big enough to challenge a principle dating back to Einstein, that, on large scales, the universe looks the same in every direction.
Roger Clowes of the University of Central Lancashire in Preston, UK, and colleagues discovered the structure using data from the Sloan Digital Sky Survey, the most comprehensive 3D map of the universe. They identified a cluster of 73 quasars, the brightly glowing cores found at the centre of some galaxies, far larger than any similar structure seen before.
Since 1982 astronomers have known that quasars tend to clump together in large quasar groups, or LQGs. “We look for quasars that have a certain separation from the next nearest quasar,” says Clowes.
The newly discovered, and appropriately named, Huge-LQG (see black circles in image) happens to be in the same region of the sky as one of the earliest known quasar clusters, which Clowes helped find in 1991. That group contains 34 quasars and measures roughly one billion light years across (red crosses), so it is dwarfed by Huge-LQG.
Read more: Largest structure challenges Einstein's smooth cosmos – space – 11 January 2013 – New Scientist.