The Giant GRB Ring is a ring of 9 gamma-ray bursts (GRBs) that may be associated with one of the largest known cosmic structures.[1] It was discovered in July 2015[2] by a team of Hungarian and American astronomers led by L.G. Balazs while analyzing data from different gamma-ray and X-ray telescopes, in particular the Swift Spacecraft.[2]
The ring of GRBs lies at a distance of about 2.8 gigaparsecs (9.1 billion light years) from Earth at the redshift between 0.78 and 0.86[2] and measures about 1.72 gigaparsecs (5.6 billion light years) in diameter,[2] making it one of the largest structures known.[3]
Typically, the distribution of GRBs in the universe appears in the sets of less than the 2σ distribution, or with fewer than two GRBs in the average data of the point-radius system. Thus, such a concentration as this appears extremely unlikely, given accepted theoretical models. Proposals include the existence of a giant supergalactic structure. This would be an extremely huge structure of the universe, with a mean size of about 5.6 billion light years. Such a supercluster can explain the significant distribution of GRBs because of its tie to star formation. If such a structure did exist, it would be one of the largest structures of the observable universe.[4]
In early July 2015, after the discovery of the Hercules–Corona Borealis Great Wall, I. Horvath, J. Hakkila and Z. Bagoly, among others, conducted a further detailed analysis of the spatial distribution of GRBs within the distant universe. Provided by more than 15 years of data from the Swift Gamma-Ray Burst Mission, amongst other ground-based telescopes, they assessed the data to see if any more structures can be seen using the method of GRB correlation. They noticed a significant clustering of GRBs within z = 0.78–0.86, with nine GRBs concentrated in that region of 43 by 30 degrees of the sky.[5] With further tests and analyses of the clustering, they found out that the sample had a higher concentration than the expected normal level, indication of a massive galactic structure within the vicinity.[2]
The authors list the following characteristics for the 9 GRBs in the ring (l and b are standard Sun-referenced galactic coordinates).[2]
| GRB ID | Redshift | Distance (Mpc) | l (deg) | b (deg) | |
|---|---|---|---|---|---|
| 040924 | 0.859 | 2866 | 149.05 | −42.52 | |
| 101225A | 0.847 | 2836 | 114.45 | −17.20 | |
| 080710 | 0.845 | 2831 | 118.43 | −42.96 | |
| 050824 | 0.828 | 2786 | 123.46 | −39.99 | |
| 071112C | 0.823 | 2772 | 150.37 | −28.43 | |
| 051022 | 0.809 | 2736 | 106.53 | −41.28 | |
| 100816A | 0.804 | 2723 | 101.39 | −32.53 | |
| 120729A | 0.800 | 2712 | 123.85 | −12.65 | |
| 060202 | 0.785 | 2672 | 142.92 | −20.54 |
It is approximately 9.1 billion light years from Earth and about 5.6 billion light years across.[6]