در کیهانشناسی فیزیکی، رشتهکهکشانها (به انگلیسی: Galaxy filament) که به نامهای کمپلکسهای ابرخوشهای (به انگلیسی: Supercluster complex) و دیوارهای بزرگ (به انگلیسی: Great wall) نیز شناختهمیشوند، یکی از بزرگترین ساختارهای کیهانی شناختهشده در جهان هستند. رشتهکهکشانها ساختارهایی عظیم به طول ۵۰ تا ۸۰ مگاپارسک هستند و مرز بین نواحی پوچ (به انگلیسی: Void) جهان را تشکیل میدهند.
In physical cosmology, galaxy filaments (subtypes: supercluster complexes, galaxy walls, and galaxy sheets) are the largest known structures in the universe. They are massive, thread-like formations, with a typical length of 50 to 80 megaparsecs h−1 (163 to 261 million light-years) that form the boundaries between large voids in the universe. Filaments consist of gravitationally bound galaxies. Parts wherein many galaxies are very close to one another (in cosmic terms) are called superclusters.
In the standard model of the evolution of the universe, galactic filaments form along and follow web-like strings 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 walls of super-galactic clusters.
Discovery of structures larger than superclusters began in the late-1980s. In 1987, astronomer R. Brent Tully of the University of Hawaii's Institute of Astronomy identified what he called the Pisces–Cetus Supercluster Complex. In 1989, the CfA2 Great Wall was discovered, followed by the Sloan Great Wall in 2003. On January 11, 2013, researchers led by Roger Clowes of the University of Central Lancashire announced the discovery of a large quasar group, the Huge-LQG, which dwarfs previously discovered galaxy filaments in size. In November 2013, using gamma-ray bursts as reference points, astronomers discovered the Hercules–Corona Borealis Great Wall, an extremely huge filament measuring more than 10 billion light-years across.
Filament subtype of filaments have roughly similar major and minor axes in cross-section, along the lengthwise axis.
- A short filament, detected by identifying an alignment of star-forming galaxies, in the neighborhood of the Milky Way and the Local Group was proposed by Adi Zitrin and Noah Brosch. The reality of this filament, and the identification of a similar but shorter filament, were the result of a study by McQuinn et al. (2014) based on distance measurements using the TRGB method.
The galaxy wall subtype of filaments have a significantly greater major axis than minor axis in cross-section, along the lengthwise axis.
Walls of Galaxies
|CfA2 Great Wall (Coma Wall, Great Wall, Northern Great Wall, Great Northern Wall, CfA Great Wall)
- 750 Mly long
250 Mly wide
20 Mly thick
|This was the first super-large large-scale structure or pseudo-structure in the universe to be discovered. The CfA Homunculus lies at the heart of the Great Wall, and the Coma Supercluster forms most of the homunculus structure. The Coma Cluster lies at the core.
|Sloan Great Wall (SDSS Great Wall)
||This was the largest known galaxy filament to be discovered, until it was eclipsed by the Hercules–Corona Borealis Great Wall found ten years later.
|Sculptor Wall (Southern Great Wall, Great Southern Wall, Southern Wall)
||8000 km/s long
5000 km/s wide
1000 km/s deep
(in redshift space dimensions)
|The Sculptor Wall is "parallel" to the Fornax Wall and "perpendicular" to the Grus Wall.
||The Grus Wall is "perpendicular" to the Fornax and Sculptor Walls.
||The Fornax Cluster is part of this wall. The wall is "parallel" to the Sculptor Wall and "perpendicular" to the Grus Wall.
|Hercules–Corona Borealis Great Wall
||3 Gpc long,
150 000 km/s deep
(in redshift space)
|The largest known structure in the universe. This is also the first time since 1991 that a galaxy filament/great wall held the record as the largest known structure in the universe.
Galaxy filaments, walls and voids form web-like structures.
Map of nearest galaxy walls
The Universe within 500 million light years, showing the nearest galaxy walls
Large Quasar Groups
Large quasar groups (LQGs) are some of the largest structures known. They are theorized to be protohyperclusters/proto-supercluster-complexes/galaxy filament precursors.
Large Quasar Groups
- longest dimension: 630 Mpc
|It was the largest known structure in the universe from 1991 to 2011, until U1.11's discovery.
- longest dimension: 780 Mpc
|Was the largest known structure in the universe for a few months, until Huge-LQG's discovery.
- characteristic size: 500 Mpc
- longest dimension: 1240 Mpc
|It was the largest structure known in the universe,
until the discovery of the Hercules–Corona Borealis Great Wall found one year later.
Maps of large-scale distribution
The universe within 1 billion light-years (307 Mpc) of Earth, showing local superclusters forming filaments and voids
Map of nearest walls, voids and superclusters
2dF survey map, containing the SDSS Great Wall
2MASS XSC infrared sky map
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