A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group, which in turn is part of the Virgo Supercluster, which is part of the Laniakea Supercluster, which is part of the Pisces–Cetus Supercluster Complex. The large size and low density of superclusters means that they, unlike clusters, expand with the Hubble expansion. The number of superclusters in the observable universe is estimated to be 10 million.
The following is a timeline of galaxies, clusters of galaxies, and large-scale structure of the universe.
The Virgo Supercluster or the Local Supercluster is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which itself contains the Milky Way and Andromeda galaxies, as well as others. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs. The Virgo SC is one of about 10 million superclusters in the observable universe and is in the Pisces–Cetus Supercluster Complex, a galaxy filament.
The Great Attractor is a region of gravitational attraction in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster of galaxies that includes the Milky Way galaxy, as well as about 100,000 other galaxies.
The Great Wall, sometimes specifically referred to as the CfA2 Great Wall, is an immense galaxy filament. It is one of the largest known superstructures in the observable universe.
The Hydra–Centaurus Supercluster, or the Hydra and Centaurus Superclusters, is a supercluster in two parts, the closest neighbour of Virgo Supercluster. It is located about 39 Mpc (127 Mly) away.
The Perseus–Pisces Supercluster is one of the largest known structures in the universe. Even at a distance of 250 million light-years, this chain of galaxy clusters extends more than 40° across the northern winter sky. The Perseus-Pisces Supercluster is one of two dominant concentrations of galaxies in the nearby universe. This supercluster also borders a prominent void, the Taurus Void, and is part of the Perseus–Pegasus Filament which stretches for roughly a billion light years.
The Horologium-Reticulum Supercluster, is a massive supercluster spanning around 550 million light-years. It has a mass of around 1017 solar masses, similar to that of the Laniakea Supercluster, which houses the Milky Way. It is centered on coordinates right ascension 03h 19m and declination −50° 02′, and spans an angular area of 12° × 12°.
The Shapley Supercluster or Shapley Concentration is the largest concentration of galaxies in our nearby universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears as a striking overdensity in the distribution of galaxies in the constellation of Centaurus. It is 650 million light-years away (z=0.046).
The Pavo–Indus Supercluster is a neighboring supercluster located about 60–70 Mpc (196–228 Mly) away in the constellations of Pavo, Indus, and Telescopium. The supercluster contains three main clusters, Abell 3656, Abell 3698, and Abell 3742.
The Leo Cluster is a galaxy cluster about 330 million light-years distant in the constellation Leo, with at least 70 major galaxies. The galaxy known as NGC 3842 is the brightest member of this cluster. Along with the Coma Cluster, it is one of the two major clusters comprising the Coma Supercluster, which in turn is part of the CfA2 Great Wall, which is hundreds of millions light years long and is one of the largest known structures in the universe.
NGC 4889 is an E4 supergiant elliptical galaxy. It was discovered in 1785 by the British astronomer Frederick William Herschel I, who catalogued it as a bright, nebulous patch. The brightest galaxy within the northern Coma Cluster, it is located at a median distance of 94 million parsecs from Earth. At the core of the galaxy is a supermassive black hole that heats the intracluster medium through the action of friction from infalling gases and dust. The gamma ray bursts from the galaxy extend out to several million light years of the cluster.
In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50/h to 80/h Megaparsecs — with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length —
The Pisces–Cetus Supercluster Complex is a galaxy filament. It includes the Laniakea Supercluster which contains the Virgo Supercluster lobe which in turn contains the Local Group, the galaxy cluster that includes the Milky Way. This filament is adjacent to the Perseus–Pegasus Filament.
The Hercules Superclusters refers to a set of two nearby superclusters of galaxies.
Abell 222 is a galaxy cluster in the constellation of Cetus. It holds thousands of galaxies together. It is located at a distance of 2.4 billion light-years from Earth.
The Corona Borealis Supercluster is a supercluster located in the constellation Corona Borealis and the most prominent example of its kind in the Northern Celestial Hemisphere. Dense and compact compared with other superclusters, its mass has been calculated to lie somewhere between 0.6 and 12 × 1016 solar masses (M⊙). It contains the galaxy clusters Abell 2056, Abell 2061, Abell 2065 (the most massive galaxy cluster within the supercluster), Abell 2067, Abell 2079, Abell 2089, and Abell 2092. Of these, Abell 2056, 2061, 2065, 2067 and A2089 are gravitationally bound and in the process of collapsing to form a massive cluster. This entity has an estimated mass of around 1 × 1016 M⊙. If there is inter-cluster mass present, then Abell 2092 may also be involved. It has been estimated to be 100 megaparsecs (330 million light-years) wide and 40 megaparsecs (130 million light years) deep. It has a redshift of 0.07, which is equivalent to a distance of around 265.5 megaparsecs (964 million light-years).
The Perseus–Pegasus Filament is a galaxy filament containing the Perseus–Pisces Supercluster and stretching for roughly a billion light-years. Currently, it is considered to be one of the largest known structures in the universe. This filament is adjacent to the Pisces–Cetus Supercluster Complex.
The Coma Filament is a galaxy filament. The filament contains the Coma Supercluster of galaxies and forms a part of the CfA2 Great Wall.
The Saraswati Supercluster is a massive galaxy supercluster about 1.2 gigaparsecs (4 billion light years) away within the Stripe 82 region of SDSS, in the direction of the constellation Pisces. It is one of the largest structures found in the universe, with a major axis in diameter of about 200 Mpc (652 million light years). It consists of at least 43 galaxy clusters, and has the mass of 2 × 1016 M☉, forming a galaxy filament.
