A large quasar group (LQG) is a collection of
quasar
A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...
s (a form of
supermassive black hole
A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (). Black holes are a class of astronomical ...
active galactic nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...
) that form what are thought to constitute the largest astronomical structures in the
observable universe
The observable universe is a Ball (mathematics), spherical region of the universe consisting of all matter that can be observation, observed from Earth; the electromagnetic radiation from these astronomical object, objects has had time to reach t ...
. LQGs are thought to be precursors to the
sheets, walls and filaments of galaxies found in the relatively nearby universe.
Prominent LQGs
On January 11, 2013, the discovery of the
Huge-LQG was announced by the
University of Central Lancashire
The University of Lancashire (previously abbreviated UCLan) is a public university based in the city of Preston, Lancashire, England. It has its roots in ''The Institution For The Diffusion Of Useful Knowledge'', founded in 1828. Previously k ...
, as the largest known structure in the universe by that time. It is composed of 74
quasar
A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...
s and has a minimum diameter of 1.4 billion
light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...
s, but over 4 billion light-years at its widest point. According to researcher and author, Roger Clowes, the existence of structures with the size of LQGs was believed theoretically impossible. Cosmological structures had been believed to have a size limit of approximately 1.2 billion light-years.
List of LQGs
Redshift, represented by "z," is a fundamental concept in astrophysics. It measures how much the light from celestial objects shift as they move away from Earth. A higher redshift value means the object is farther away in the universe.
See also
*
List of largest cosmic structures
This is a list of the largest cosmic structures so far discovered. The unit of measurement used is the light-year (distance traveled by light in one Julian year (astronomy), Julian year; approximately 9.46 trillion Metre, kilometres).
This list ...
*
Large-scale structure of the cosmos
The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of th ...
References
Further reading
* R. G. Clowes; "Large Quasar Groups - A Short Review"; 'The New Era of Wide Field Astronomy', ''
ASP Conference Series'', Vol. 232.; 2001; Astronomical Society of the Pacific; ;
{{galaxy
*
*Large Quasar Group