An image of the distribution of GRBs on the sky at a distance of 7 billion light years, centred on the newly discovered ring. The positions of the GRBs are marked by blue dots and the Milky Way is indicated for reference, running from left to right across the image. Credit: L. Balazs.
5 billion light years is a distance almost inconceivable, even on a cosmic scale ie 35,000 galaxies the size of our Milky Way are needed to cover that distance. Hungarian-U.S. team have now found a structure this big really exists in the observable universe.
The researchers found a ring of 9 gamma ray bursts (GRBs)—the most luminous events in the universe—5B light yrs in diameter, and having a nearly regular circular shape, with a 1 in 20,000 probability of the GRBs being in this distribution by chance. “Until now GRBs are the only objects for which we know the spatial distribution in the whole observable universe. All other objects are complete only in a restricted part of the sky… such a regular circular structure was a surprise,” Balazs who led the team.
The newly-found ring-shaped feature is large enough to contradict the cosmological principle (CP), which sets a theoretical limit of 1.2 billion light years for the largest structures. Although they claim to have found evidence for a regular structure, the apparent shape of this ring is based only on a visual impression. The ring is probably not a real physical structure. But further studies are needed to reveal whether or not the structure could have been produced by a low-frequency spatial harmonic of the large-scale matter density distribution or of universal star-forming activity.
“It would be important to increase the number of GRBs with known redshift, consequently with known distances, and to study the distribution of galaxies potentially hosting GRBs in more detail,” Balazs said.
GRBs are the brightest electromagnetic events known releasing as much energy in a few seconds as the Sun does over its 10yr lifetime. GRBs are believed to be the result of massive stars collapsing into black holes.
GRBs have 2 basic types. The short duration ones < 2secs, are formed by 2 coalescing neutron stars, while longer ones resulted in collapsing stars of 20 to 40 solar masses. Most GRBs are resulted in collapsing high-mass stars and are rare. The high-mass stars have short lifetimes; thus, GRBs prefer those galaxy hosts having considerable star-forming activity. The known number of GRBs are now >2000 and is steadily increasing with ongoing observations.
http://phys.org/news/2015-09-giant-ring-like-universe.htmljCp
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