Astronomers have found the largest structures ever discovered in the universe—filaments of galaxies 200 million light-years in length that date from just 2 billion years after the Big Bang.
The filaments contain 30 giant pockets of gas, each of which may be as much as 10 times the mass of the Milky Way. Such large structures were rare in the early universe and are probably the precursors of the type of galaxy clusters seen today, says Ryosuke Yamauchi of Tohoku University in Sendai, Japan. Yamauchi is part of a team that used the Subaru and Keck II telescopes atop Hawaii’s Mauna Kea to study a patch of sky known to contain a high density of galaxies.
Subaru images, combined with velocity measurements from Keck, revealed much fainter objects than had previously been discovered in the region. The pockets of gas, first discovered 6 years ago, are known as Lyman-alpha blobs. The Subaru observatory announced the findings on July 26.
Theory suggests that the seeds of these large structures formed during the birth of the universe, comments John Peacock of the Royal Observatory of Edinburgh in Scotland.