Pisces–Cetus Supercluster Complex

The Pisces–Cetus Supercluster Complex (Pisces–Cetus SCC) or the local superstructure^[5] is a galaxy supercluster complex (SCC) that includes the Virgo Supercluster as its outlying member (later confirmed to be part of the Laniakea),^[5] which in turn contains the Local Group, the galaxy group that includes the Milky Way.^[1] The complex was named after the Pisces–Cetus Superclusters, which are its richest and most prominent superclusters and reside in as its core and of its main plane, located at roughly 200 megaparsecs (652 million light-years; 6.17×10²¹ kilometres) away from Earth.^[2] An supercluster complex is defined as container of several dozens of rich clusters and large superclusters.^[2]

Pisces–Cetus Supercluster Complex
Observation data (Epoch J2000)
Constellation(s)	Pisces and Cetus (Pisces–Cetus Supercluster)[1][2]
Right ascension	00h 33m [3][4]
Declination	−21° 00′[3][4]
Parent structure	Local Hole
Major axis	1,240 Mly (380 Mpc)h−1 0.70[5]
Minor axis	520 Mly (160 Mpc)h−1 0.75[1]: 5
Distance	650 Mly (200 Mpc) (Pisces–Cetus Supercluster)[1][2]
Binding mass	~1018[1][2] M☉
Other designations
Pisces–Cetus Supercluster Complex, Pisces–Cetus Complex, Pisces–Cetus SCC, Pisces–Cetus Filament, Local Supercluster Complex

This filament is adjacent to the Perseus–Pegasus Filament.^[6]

Observational history

Astronomer R. Brent Tully of the University of Hawaii's Institute of Astronomy discovered a very massive agglomeration that includes the Local and Pisces–Cetus Superclusters in 1986,^[1] and identified it as the "extended Pisces–Cetus Supercluster",^[1] and later the Pisces–Cetus Supercluster Complex in 1987.^[7] In addition, four more other nearby supercluster complexes within a redshift of z = 0.1 (roughly 340 megaparsecs) have also been discovered, including Ursa Major, Hercules-Corona Borealis, Leo, and Aquarius Supercluster Complexes.^[2] The Aquarius Supercluster Complex was known to contain 25 rich galaxy clusters and is composed of two parts, which are both the Aquarius Region and the Aquarius-Capricornus Region.^[2] It along with Pisces–Cetus Supercluster Complex have been shown to contains most of the 114 southern Abell clusters. Only 28 are not associated with these two main complexes, with no other association having more than four members.^[2]

Following the discovery of those supercluster complexes at the end of the 20th century, more other supercluster complexes were later identified such as Sloan Great Wall and BOSS Great Wall.^[8][9]

Extent

The Pisces–Cetus Supercluster Complex is estimated to be about 380 megaparsecs (1.24 billion light-years; 1.17×10²² kilometres) long and 160 megaparsecs (520 million light-years; 4.9×10²¹ kilometres) wide, making it one of the largest structures known in the observable universe. This brings it to roughly the theoretical limit per the Cosmological Principle. Despite that, larger sizes have been suggested for other structures such as Quipu superstructure, Clowes–Campusano LQG and U1.11, along with the disputed and unconfirmed Huge-LQG, Giant GRB Ring, and Hercules–Corona Borealis Great Wall.

61 rich clusters comprise the complex, which is estimated to have a total mass of approximately 10¹⁸ times that of the mass of the Sun (M_☉).^[2] According to the discoverer, the complex is composed of 5 parts:

1. The Pisces–Cetus Supercluster
2. The Perseus–Pegasus chain, including the Perseus–Pisces Supercluster
3. The Pegasus–Pisces chain
4. The Sculptor region, including the Sculptor Supercluster and Hercules Supercluster
5. The Laniakea Supercluster,^[5] which contains our Virgo Supercluster (Local Supercluster) as well as the Hydra–Centaurus Supercluster.^[2]

With its mass of 10¹⁵ M_☉, our Virgo Supercluster accounts only for 0.1 percent of the total mass of the complex.

Image

Map of the local universe within a billion light-years from Earth, including the Pisces–Cetus Supercluster Complex, which is the very long chain of galaxies from the Pisces–Cetus Superclusters, Sculptor Superclusters, the Perseus–Pisces Supercluster and the Laniakea Supercluster (here shown as the former Virgo, Hydra, and Centaurus Superclusters)

See also

• Entropy
• Fossil galaxy group
• Galactic orientation
• Intracluster medium
• Large-scale structure of the universe
• List of galaxy groups and clusters
• Timeline of galaxies and large scale structures