A Hungarian-US team of astronomers have found what may be the largest structure in the observable universe, a circular ring of nine gamma ray bursts and hence nine galaxies that stretches five billion light years across.
Gamma-ray bursts (GRBs) are the most luminous events in the observable universe. These events occur when massive stars in a galaxy collapse into black holes. Astronomers have used these GRBs to locate and map the locations of their distant host galaxies. Such bursts are cataloged in the Gamma Ray Burst Online Index, a precise listing of burst distances and locations, creating a cosmic map.
Using a number of space-based and Earth-based observatories, U.S. and Hungarian scientists detected the ring's galaxies - all at roughly the same distance from our planet, about seven billion light years away - using gamma ray bursts.The scientists, led by Professor Lajos Balazs of Konkoly Observatory in Budapest, report their work in a paper in Monthly Notices of the Royal Astronomical Society.
The galaxies are in a circle that takes up 36 degrees of the sky - 70 times the diameter of the moon when it's full - which suggests the ring is at least five billion light years across.
According to the Cosmological Principle, a cosmological structure could be up to 1.2 billion light years across. The new discovery challenges this theory as the cosmic ring found is nearly five times as big. According to Professor Balazs there is only a 1 in 20,000 probability of the GRBs being in this distribution randomly.
In the voice of the researchers, “If the ring represents a real spatial structure, then it has to be seen nearly face-on because of the small variations of GRB distances around the object's center. The ring could though instead be a projection of a sphere, where the GRBs all occurred within a 250 million year period, a short timescale compared with the age of the universe.”
The team now wants to know more about the ring. They have no clear idea how the ring came into existence. Many models of the observable universe have predicted voids and string like formations. However, the newly discovered ring is larger any other void discovered previously. Prof Balazs comments: “If we are right, this structure contradicts the current models of the universe. It was a huge surprise to find something this big – and we still don’t quite understand how it came to exist at all.”
Knowledge regarding how the ring came into existence may approve of theories on the evolutions of galaxies. However, in the opposite circumstance, the astronomers may have to revise their theories. The team aims at finding out the truth.
Source: Royal Astronomical Society
- "A giant ring-like structure at 0.78 < z < 0.86 displayed by GRBs" - L. G. Balázs, Z. Bagoly, J. E. Hakkila, I. Horváth, J. Kóbori, I. I. Rácz and L. V. Tóth - Monthly Notice of the Royal Astronomical Society (July 24, 2015) - doi: 10.1093/mnras/stv1421
Featured image: 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.