Harculis Corona Borealis Great Wall
Hercules–Corona Borealis Great Wall or the Great Wall is the largest-known cosmic structure in the known universe, measuring about 10 billion light years in length (for aspects, the observable universe is approximately 93 billion light years in diameter). This massive super cosmic structure is a region of the sky seen in the data set mapping of gamma-ray bursts (GRBs) that has been found to have an unusually higher condensation of similarly distanced GRBs than the expected mean distribution. It was discovered in early November 2013 by the team of American and Hungarian astronomers led by István Horváth, Jon Hakkila and Zsolt Bagoly while exploring data from the Swift Gamma-Ray Burst Mission, together with other data from ground-based telescopes It is the largest-known formation in the observable universe, exceeding the size of the former largest cosmic structure Huge-LQG by about two times.
Harculis Corona Borealis Great Wall
Observation data( Epoch J2000)
Constellation(s) : Harculis, Corona, Borealis, Lyra, Bootes and Draco
Right ascention: 17h 0m
Major Axis: 3 Gpc
Minor axis : 2.2 Gpc
Red shift : 1.6 - 2.1
Distance : 9.612 - 10.538 billion
(Co - moving) light years
The overdensity located at the Second, Third and Fourth Galactic Quadrants (NQ2, NQ3 and NQ4) of the sky. Thus, it located in the Northern Hemisphere, centered on the border of the constellations Draco and Hercules. The entire structure consists of about 19 GRBs with the redshift ranges between 1.6 and 2.1.
Typically, the format of GRBs in the universe appears in the sets of less than the 2σ distribution, or with less than two GRBs in the average data of the point-radius system. One possible explication of this concentration is the Hercules–Corona Borealis Great Wall. The wall has a average size in excess of 6 to 10 billion light-years. Such a massive supercluster can interpret the important distribution of GRBs because of its tie to star formation.
Doubt has been placed on the presence of the structure in other studies, positing that the structure was found through biases in certain statistical tests, without envisage the full effects of evanescence.
Discovery of Harculis Corona Borealis Great Wall
The overdensity was discovered using data from various space telescopes operating at gamma-ray and X-ray wavelengths, plus some data from ground-based telescopes. By the ending of 2012 they successfully listed 283 GRBs and counted their redshifts spectroscopically. They subdivided them to various group subsamples of various redshifts, primarily with five groups, six groups, seven groups and eight groups, but each group section in the tests suggest a weak anisotropy and concentration, but this is not the case when it is subdivided to nine groups, each containing 31 GRBs; they noticed a important clustering of GRBs of the fourth subsample (z = 1.6 to 2.1) with 19 of the 31 GRBs of the subsample are concentrated within the proximity of the Second, Third and Fourth Northern Galactic Quadrants (NQ2, NQ3 and NQ4) measuring no less than 120 degrees of the sky. Under current stellar evolutional models GRBs are only based by neutron star collision and collapse of massive stars, and as such, stars causing these events are only discovered in regions with more matter in general. Using the two-point Kolmogorov–Smirnov test, a nearest-neighbor test, and a Bootstrap point-radius system , they found the statistical significance of this observation to be less than 0.05%. The possible binomial possibility to find a clustering was p=0.0000055. It is later reported in the paper that the clustering may be associated with a previously unknown supermassive cosmic structure.
Nomenclature
The authors of the paper concluded that a structure was the possible explication of the clustering, but they never connected any name with it. Hakkila stated that "During the process, we were more worried with whether it was real or not." The term "Hercules–Corona Borealis Great Wall" was coined by a Filipino teenager from Marikina on Wikipedia, after reading a Discovery News report three weeks after the structure's discovery in 2013. The name was used by Jacqueline Howard, on her "Talk Nerdy to Me" video series and Hakkila would later use the name.
The term is misleading, since the clustering occupies a region much larger than the constellations Hercules and Corona, Borealis constellation . In fact, it shrouds the region from Boötes to as far as the Zodiac constellation Gemini. In addition, the clustering is somewhat circle in shape, which is more likely a supercluster, in contrast to an extended shape of a galaxy wall. Another name, the Great GRB Wall, was raised in a later paper.
Characteristics of Harculis Corona Borealis Great Wall
The paper states that "14 of the 31 GRBs are condensed within 45 degrees of the sky",[3] which translates to the size of about 10 billion light-years in its longest amount, which is about one ninth (10.7%) of the diameter of the known universe. However, the clustering contains 19 to 22 GRBs, and spans a length three times longer than the residual 14 GRBs. Indeed, the clustering roods over 20 constellations and covers 125 degrees of the sky, or about 15,000 square degrees in total area, which translates to about 18 to 23 billion light-years in length. It lies at redshift 1.6 to 2.1.
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