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A large quasar group (LQG) is a collection of quasars (a form of supermassive black hole active galactic nuclei) that form what are thought to constitute the largest astronomical structures in the observable universe. LQGs are thought to be precursors to the sheets, walls and filaments of galaxies found in the relatively nearby universe.[1]
On January 11, 2013, the discovery of the Huge-LQG 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.[2] 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.[3][4]
Redshift, denoted as "z," is a fundamental concept in astrophysics used to measure the spectral line shift in light emitted by celestial objects like quasars due to their motion away from Earth. In the table below, higher redshift values directly correspond to greater cosmic distances.
| LQG | Date | Mean Distance | Dimension | # of quasars | Notes |
|---|---|---|---|---|---|
| Webster LQG (LQG 1) |
1982 | z=0.37 | 100 Mpc | 5 | First LQG discovered. At the time of its discovery, it was the largest structure known.[1][4][5] |
| Crampton–Cowley–Hartwick LQG (LQG 2, CCH LQG, Komberg-Kravtsov-Lukash LQG 10) |
1987 | z=1.11 | 60 Mpc | 28 | Second LQG discovered [1][4][6] |
| Clowes–Campusano LQG (U1.28, CCLQG, LQG 3) |
1991 | z=1.28 |
|
34 | Third LQG discovered [4][7] |
| U1.90 | 1995 | z=1.9 | 120 Mpc/h | 10 | Discovered by Graham, Clowes, Campusano.[1][6][8] |
| 7Sf Group (U0.19) |
1995 | z=0.19 | 60 Mpc/h | 7 | Discovered by Graham, Clowes, Campusano; this is a grouping of 7 Seyfert galaxies.[1][6][8] |
| Komberg–Kravtsov–Lukash LQG 1 | 1996 | z=0.6 | R=96 Mpc/h | 12 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 2 | 1996 | z=0.6 | R=111 Mpc/h | 12 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 3 | 1996 | z=1.3 | R=123 Mpc/h | 14 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 4 | 1996 | z=1.9 | R=104 Mpc/h | 14 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 5 | 1996 | z=1.7 | R=146 Mpc/h | 13 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 6 | 1996 | z=1.5 | R=94 Mpc/h | 10 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 7 | 1996 | z=1.9 | R=92 Mpc/h | 10 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 8 | 1996 | z=2.1 | R=104 Mpc/h | 12 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 9 | 1996 | z=1.9 | R=66 Mpc/h | 18 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 11 | 1996 | z=0.7 | R=157 Mpc/h | 11 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Komberg–Kravtsov–Lukash LQG 12 | 1996 | z=1.2 | R=155 Mpc/h | 14 | Discovered by Komberg, Kravtsov, Lukash.[1][6] |
| Newman LQG (U1.54) |
1998 | z=1.54 | 150 Mpc/h | 21 | Discovered by P.R. Newman[9] et al. This structure is parallel to the CCLQG, with its discovery, suggesting that the cellular structure of sheets and voids already existed in this era, as found in later void bubbles and walls of galaxies.,[1][7] |
| Tesch–Engels LQG | 2000 | z=0.27 | 140 Mpc/h | 7 | The first X-ray selected LQG.[1] |
| U1.11 | 2011 | z=1.11 |
|
38 | [4][7] |
| Huge-LQG (U1.27) |
2013 | z=1.27 |
|
73 | The largest structure known in the observable universe[4][10] until it was eclipsed by the Hercules–Corona Borealis Great Wall found one year later.[11][12][13] |
