Supercluster

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A map of the superclusters and voids nearest to Earth Superclusters atlasoftheuniverse.gif
A map of the superclusters and voids nearest to Earth

A supercluster is a large group of smaller galaxy clusters or galaxy groups; [1] they are among the largest known structures of the universe. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in turn is part of the Virgo Supercluster, which is part of the Laniakea Supercluster. [2] 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. [3]

Contents

Existence

The Abell 901/902 supercluster is located a little over two billion light-years from Earth. An Intergalactic Heavyweight.jpg
The Abell 901/902 supercluster is located a little over two billion light-years from Earth.

The existence of superclusters indicates that the galaxies in the Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to some dozens of galaxies and clusters up to several thousand galaxies. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.

Their existence was first postulated by George Abell in his 1958 Abell catalogue of galaxy clusters. He called them "second-order clusters", or clusters of clusters. [5]

Superclusters form massive structures of galaxies, called "filaments", "supercluster complexes", "walls" or "sheets", that may span between several hundred million light-years to 10 billion light-years, covering more than 5% of the observable universe. These are the largest structures known to date. Observations of superclusters can give information about the initial condition of the universe, when these superclusters were created. The directions of the rotational axes of galaxies within superclusters are studied by those who believe that they may give insight and information into the early formation process of galaxies in the history of the Universe. [6]

Interspersed among superclusters are large voids of space where few galaxies exist. Superclusters are frequently subdivided into groups of clusters called galaxy groups and clusters.

Although superclusters are supposed to be the largest structures in the universe, according to the Cosmological principle, larger structures have been observed in surveys, including the Sloan Great Wall. [7]

List of superclusters

Galaxy superclusterDataNotes
Laniakea Supercluster
  • z = 0.000
  • Length = 153 Mpc (500 million light-years)
The Laniakea Supercluster is the supercluster that contains the Virgo Cluster, Local Group, and by extension on the latter, our galaxy; the Milky Way. [2]
Virgo Supercluster
  • z= 0.000
  • Length = 33 Mpc (110 million light-years)
It contains the Local Group with our galaxy, the Milky Way. It also contains the Virgo Cluster near its center, and is sometimes called the Local Supercluster. It is thought to contain over 47,000 galaxies.

In 2014, the newly announced Laniakea Supercluster subsumed the Virgo Supercluster, which became a component of the new supercluster. [8]

Hydra-Centaurus Supercluster It is composed of two lobes, sometimes also referred to as superclusters, or sometimes the entire supercluster is referred to by these other two names
  • Hydra Supercluster
  • Centaurus Supercluster

In 2014, the newly announced Laniakea Supercluster subsumed the Hydra-Centaurus Supercluster, which became a component of the new supercluster. [8]

Pavo-Indus Supercluster

In 2014, the newly announced Laniakea Supercluster subsumed the Pavo-Indus Supercluster, which became a component of the new supercluster. [8]

Southern Supercluster

Includes Fornax Cluster (S373), Dorado and Eridanus clouds. [9]

Saraswati Supercluster Distance = 4000 Million light years (1.2 Gpc)

Length = 652 Million light-years

The Saraswati Supercluster consists of 43 massive galaxy clusters such as Abell 2361 and has a mass of about 2 x 1016  M and is seen in the Pisces constellation

Nearby superclusters

Galaxy superclusterDataNotes
Perseus-Pisces Supercluster
Coma Supercluster Forms most of the CfA Homunculus, the center of the CfA2 Great Wall galaxy filament
Sculptor Superclusters SCl 9
Hercules Superclusters SCl 160
Leo Supercluster SCl 93
Ophiuchus Supercluster
  • 17h 10m−22°
  • cz=8500–9000 km/s (centre)
  • 18 Mpc x 26 Mpc
Forming the far wall of the Ophiuchus Void, it may be connected in a filament, with the Pavo-Indus-Telescopium Supercluster and the Hercules Supercluster. This supercluster is centered on the cD cluster Ophiuchus Cluster, and has at least two more galaxy clusters, four more galaxy groups, several field galaxies, as members. [10]
Shapley Supercluster
  • z=0.046.(650 Mly away)
The second supercluster found, after the Local Supercluster.

Distant superclusters

Galaxy superclusterDataNotes
Pisces-Cetus Supercluster
Boötes Supercluster SCl 138
Horologium-Reticulum Supercluster
z=0.063 (700 Mly)
Length = 550 Mly
Corona Borealis Supercluster
z=0.07 [11]
Columba Supercluster
Aquarius Supercluster
Aquarius B Supercluster
Aquarius-Capricornus Supercluster
Aquarius-Cetus Supercluster
Bootes A Supercluster
Caelum Supercluster
z=0.126 (1.4 Gly)
Length = 910 Mly
The largest galaxy supercluster.
Draco Supercluster
Draco-Ursa Major Supercluster
Fornax-Eridanus Supercluster
Grus Supercluster
Leo A Supercluster
Leo-Sextans Supercluster
Leo-Virgo Supercluster SCl 107
Microscopium Supercluster SCl 174
Pegasus-Pisces Supercluster SCl 3
Perseus-Pisces Supercluster SCl 40
Pisces-Aries Supercluster
Ursa Majoris Supercluster
Virgo-Coma Supercluster SCl 111

Extremely distant superclusters

Galaxy superclusterDataNotes
Hyperion proto-supercluster z=2.45This supercluster at the time of its discovery in 2018 was the earliest and largest proto-supercluster found to date. [12] [13]
Lynx Supercluster z=1.27Discovered in 1999 [14] (as ClG J0848+4453, a name now used to describe the western cluster, with ClG J0849+4452 being the eastern one), [15] it contains at least two clusters RXJ 0848.9+4452 (z=1.26) and RXJ 0848.6+4453 (z=1.27) . At the time of discovery, it became the most distant known supercluster. [16] Additionally, seven smaller groups of galaxies are associated with the supercluster. [17]
SCL @ 1338+27 at z=1.1

z=1.1

Length=70Mpc

A rich supercluster with several galaxy clusters was discovered around an unusual concentration of 23 QSOs at z=1.1 in 2001. The size of the complex of clusters may indicate a wall of galaxies exists there, instead of a single supercluster. The size discovered approaches the size of the CfA2 Great Wall filament. At the time of the discovery, it was the largest and most distant supercluster beyond z=0.5 [18] [19]
SCL @ 1604+43 at z=0.9 z=0.91This supercluster at the time of its discovery was the largest supercluster found so deep into space, in 2000. It consisted of two known rich clusters and one newly discovered cluster as a result of the study that discovered it. The then known clusters were Cl 1604+4304 (z=0.897) and Cl 1604+4321 (z=0.924), which then known to have 21 and 42 known galaxies respectively. The then newly discovered cluster was located at 16h 04m 25.7s, +43° 14 44.7 [20]
SCL @ 0018+16 at z=0.54 in SA26 z=0.54This supercluster lies around radio galaxy 54W084C (z=0.544) and is composed of at least three large clusters, CL 0016+16 (z=0.5455), RX J0018.3+1618 (z=0.5506), RX J0018.8+1602 . [21]
MS 0302+17

z=0.42

Length=6Mpc

This supercluster has at least three member clusters, the eastern cluster CL 0303+1706, southern cluster MS 0302+1659 and northern cluster MS 0302+1717. [22]

Diagram

Location of Earth (9x1-English Annot-small).png
A diagram of Earth's location in the observable Universe and neighbouring superclusters of galaxies. ( Alternative image.)

See also

Related Research Articles

Local Group Group of galaxies that includes the Milky Way

The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1022 metres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kpc (3×10^6 ly; 2×1022 m) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.

Virgo Supercluster Galactic supercluster containing the Virgo Cluster

The Virgo Supercluster or the Local Supercluster is a mass concentration of galaxies containing the Virgo Cluster and Local Group, which in turn contains the Milky Way and Andromeda galaxies. 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.

Great Attractor An apparent gravitational anomaly at the center of the local Laniakea Supercluster

The Great Attractor is a gravitational anomaly in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster. The observed anomalies suggest a localized concentration of mass millions of times more massive than the Milky Way. However, it is inconveniently obscured by our own Milky Way's galactic plane, lying behind the Zone of Avoidance (ZOA), so that, in visible light wavelengths, the Great Attractor is difficult to observe directly.

Messier 94 Spiral galaxy in the constellation Canes Venatici

Messier 94 is a spiral galaxy in the mid-northern constellation Canes Venatici. It was discovered by Pierre Méchain in 1781, and catalogued by Charles Messier two days later. Although some references describe M94 as a barred spiral galaxy, the "bar" structure appears to be more oval-shaped. The galaxy has two ring structures.

Lyman-alpha blob

In astronomy, a Lyman-alpha blob (LAB) is a huge concentration of a gas emitting the Lyman-alpha emission line. LABs are some of the largest known individual objects in the Universe. Some of these gaseous structures are more than 400,000 light years across. So far they have only been found in the high-redshift universe because of the ultraviolet nature of the Lyman-alpha emission line. Since Earth's atmosphere is very effective at filtering out UV photons, the Lyman-alpha photons must be redshifted in order to be transmitted through the atmosphere.

Pavo–Indus Supercluster Neighboring supercluster in the constellations Pavo,Indus and Telescopium

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.

Antlia Cluster Galaxy cluster in the constellation Antlia

The Antlia Cluster is a cluster of galaxies located in the Hydra-Centaurus Supercluster. The Antlia Cluster is the third-nearest to the Local Group after the Virgo Cluster and Fornax Cluster. Antlia's distance from Earth is 40.5 megaparsecs to 40.9 Mpc (133.4 Mly) and can be viewed from Earth in the constellation Antlia. The Antlia Cluster should not be confused with the Antlia Dwarf galaxy.

Location of Earth Knowledge of the location of Earth

Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of the heliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars. By the 20th century, observations of spiral nebulae revealed that the Milky Way galaxy was one of billions in an expanding universe, grouped into clusters and superclusters. By the end of the 20th century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids. Superclusters, filaments and voids are the largest coherent structures in the Universe that we can observe. At still larger scales the Universe becomes homogeneous, meaning that all its parts have on average the same density, composition and structure.

Galaxy filament Largest structures in the universe, made of galaxies

In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of gravitationally bound galaxy superclusters. These massive, thread-like formations can reach 80 megaparsecs h−1 and form the boundaries between large voids.

Void (astronomy) Vast empty spaces between filaments with few or no galaxies

Cosmic voids are vast spaces between filaments, which contain very few or no galaxies. The cosmological evolution of the void regions differs drastically from the evolution of the Universe as a whole: there is a long stage when the curvature term dominates, which prevents the formation of galaxy clusters and massive galaxies. Hence, although even the emptiest regions of voids contain more than ~15% of the average matter density of the Universe, the voids look almost empty for an observer. Voids typically have a diameter of 10 to 100 megaparsecs ; particularly large voids, defined by the absence of rich superclusters, are sometimes called supervoids. They were first discovered in 1978 in a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory.

The Taurus Void is a vast, near-empty region of space situated between the Perseus-Pisces Supercluster and the Virgo Supercluster. The Taurus void is unique because of its relatively close proximity to Earth, and because it helps to define the edge of latter's home supercluster, the Virgo Supercluster. Despite its close proximity to Earth, the Taurus Void is not well-studied because it is partially obscured by the Milky Way when viewed from Earth. In contrast to its ambiguous boundary in the section of sky obscured by the Milky Way, the Taurus Void has a very well-defined boundary with the Perseus-Pisces supercluster.

The Lynx Supercluster was discovered in 1999 as ClG J0848+4453, a name now used to describe the western cluster, with ClG J0849+4452 being the eastern one. It contains at least two clusters, designated RXJ 0848.9+4452 and RXJ 0848.6+4453. At the time of discovery, it was the most distant known supercluster with a comoving distance of 12.9 billion light years. Additionally, seven smaller groups of galaxies are associated with the supercluster. Through electromagnetic radiation and how it reacts with matter, we have been able to find three groupings of stars and two x-ray clusters within the Lynx.

KBC Void Large, comparatively empty region of space

The KBC Void is an immense, comparatively empty region of space, named after astronomers Ryan Keenan, Amy Barger, and Lennox Cowie, who studied it in 2013. The existence of a local underdensity has been the subject of many pieces of literature and research articles.

Caelum Supercluster

The Caelum Supercluster, also known as SCl 59, may be a massive supercluster; spanning 910 million light-years, it is perhaps the largest galaxy supercluster in the universe. It has a mass of 2×1017 solar masses, 1.7 times the mass of Laniakea Supercluster and of Horologium Supercluster. It is centered on coordinates right ascension 04h 43m and declination −33° 30′.

NGC 7418 Intermediate spiral galaxy in the constellation Grus

NGC 7418 is an intermediate spiral galaxy located in the constellation Grus. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 7418 is about 60,000 light years across. It was discovered by John Herschel on August 30, 1834.

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