Filaments & Walls

Filaments are long, thin structures of galaxies like threads, much longer than their cross sections.  Walls are much wider but flatter than filaments.  They can span up to half a billion Megaparsecs in length,.  Here are some examples. 
The Standard Model cannot account for such large structures, so in the actual cosmology it is hypothesized that such structures as the Great Wall form along and follow web-like threads of dark matter. It is thought that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts baryonic matter, and it is this normal matter that astronomers see forming long, thin filaments and walls of super-galactic clusters.
Pisces-Cetus Filament AA Originally called the Pisces-Cetus Supercluster Complex when it was first identified in 1987 by Brent Tully.  It was one of the first of the truly enormous structures found at a level above superclusters.  It is a galaxy filament that includes the Virgo Supercluster, to which our galaxy,  the Milky Way, belongs.  It is over 300 Mpc long, and nearly 50 Mpc wide (about 1 billion x 150 million light years). 
Perseus-Pegasus Filament   Adjacent to the Pisces-Cetus filament, it includes the Perseus-Pisces Supercluster, and is nearly 300 Mpc long.
Sloan Great Wall   The Sloan Great Wall was first identified in 2003 as part of the Sloan Digital Sky Survey, and is probably the largest structure in the known Universe.  It is around 420 Mpc (c. 1.4 billion light years) long, and around 300 Mpc away, though estimates do vary.  Some parts of it are not gravitationally bound together and and may never be, so in some ways, we should not really consider it as a single coherent structure.  Nevertheless, it is impressive.  Shown in the image to the left with the Shapley Supercluster, and parts of the Pisces-Cetus filament and Horologium-Reticulum Supercluster.
Great (Coma) Wall   Found in 1989, the Great Wall (also called the Coma Wall), is another enormous structure at about 185 Mpc long, 80 Mpc wide and 5 Mpc thick (about 600 million x260 million x 15 million light years).  It could extend much farther but the gas and dust in the Milky Way's zone of avoidance obscures what can be seen.  It is somewhat over 60 Mpc away. 
Sculptor Wall   The map to the left shows the position of the Sculptor Wall, the red curved line, in relation to the Milky Way, which is at the bottom.  Towards the bottom, and to the right of the Sculptor Wall, from approximately 100 to 300 light-years, there is a rectangular region with a very low density of galaxies.  This is called the Sculptor Void.
Centaurus Wall   Conjectural, but could contain the smaller Fornax Wall and the Centaurus Supercluster.  There is also a suggestion that out local supercluster, the Virgo supercluster, could be a part of this wall. 
Great Attractor or Norma Wall   Another conjectural object suggested to represent the Great Attractor.  It would include the Norma Cluster.
Astronomy & Cosmology

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Large Scale Structure of the Universe

Willem Schaap
WILLIAM & DEBORAH HILLYARD
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