Astronomers Find the Largest Celestial Object Ever Discovered

Monday, 14 March 2016 - 1:25PM
Monday, 14 March 2016 - 1:25PM
Astronomers Find the Largest Celestial Object Ever Discovered
Astronomers have found the largest object in the universe--so far: a structure made up of galaxy superclusters, aptly named the BOSS Great Wall.

A galaxy cluster is a structure that consists of hundreds or even thousands of galaxies bound together by gravity. They were once thought to be the largest structures in the universe, until superclusters were discovered, which consist of large groups of galaxy clusters clumped together. These superclusters can then link together to form "Great Walls," like the Laniakea, a structure which contains our own Milky Way galaxy. As a result, the universe on a large scale resembles a massive spiderweb of galaxies surrounding dark, empty voids.

The BOSS Great Wall is the biggest structure of its kind that astronomers have been able to detect. It is one billion light years across, and is made up of four superclusters (830 galaxies that we can see so far) connected by gaseous filaments as part of the cosmic web. It is estimated to have a mass that is 10,000 times the mass of our Milky Way galaxy, and is two-thirds bigger than the Sloan Great Wall. 

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"It was so much bigger than anything else in this volume," Heidi Lietzen of the Canary Islands Institute of Astrophysics, who leads the team that discovered the superstructure, told New Scientist.
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However, some scientists are dubious as to whether the group of superclusters can actually be considered to be a single structure:

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"I don't entirely understand why they are connecting all of these features together to call them a single structure," said Allison Coil of the University of California in San Diego. "There are clearly kinks and bends in this structure that don't exist, for example, in the Sloan Great Wall."
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However, Brent Tully, who discovered the Laniakea structure, claims that determining whether a group of superclusters constitutes a single structure is slightly subjective, but that a density of five galaxies across--which the BOSS fulfills--is the generally accepted criterion. We may get a different answer if we were able to determine whether the galaxies are moving together, but as of now, the structures are too far away to measure. 
Science
Space

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