A large quasar group (LQG) is a collection of
quasars (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 ob ...
active galactic nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...
) that form what are thought to constitute the largest astronomical structures in the
observable universe
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these ob ...
. 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
The Huge Large Quasar Group, (Huge-LQG, also called U1.27) is a possible structure or pseudo-structure of 73 quasars, referred to as a large quasar group, that measures about 4 billion light-years across. At its discovery, it was identified as t ...
was announced by the
University of Central Lancashire, as the largest known structure in the universe by that time. It is composed of 74
quasars and has a minimum diameter of 1.4 billion
light-years, 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
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; approximately 9.46 trillion kilometres).
This list includes superclusters, galaxy ...
*
Large-scale structure of the cosmos
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these obj ...
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