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. Click here for a full size image
A Hungarian-US team of astronomers have found what appears to be the largest feature in the observable universe: a ring of nine gamma ray bursts – and hence galaxies - 5 billion light years across. The scientists, led by Prof Lajos Balazs of Konkoly Observatory in Budapest, report their work in a paper in Monthly Notices of the Royal Astronomical Society.
Gamma-ray bursts (GRBs) are the most luminous events in the universe,
releasing as much energy in a few seconds as the Sun does over its 10
billion year lifetime. They are thought to be the result of massive
stars collapsing into black holes. Their huge luminosity helps astronomers to map out the location of distant galaxies, something the team exploited.
The GRBs that make up the newly discovered ring were observed using a variety of space- and ground-based observatories (the sample is listed in the Gamma Ray Burst Online Index).
They appear to be at very similar distances from us – around 7 billion
light years – in a circle 36° across on the sky, or more than 70 times
the diameter of the Full Moon. This implies that the ring is more than 5
billion light years across, and according to Prof Balazs there is only a
1 in 20,000 probability of the GRBs being in this distribution by
chance.
Most current models indicate that the structure of the cosmos is uniform on the largest scales. This ‘Cosmological Principle’ is backed up by observations of the early universe and its microwave background signature, seen by the WMAP and Planck
satellites. Other recent results and this new discovery challenge the
principle, which sets a theoretical limit of 1.2 billion light years for
the largest structures. The newly discovered ring is almost five times
as large.
“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 centre. 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.”
A spheroidal ring projection would mirror the strings of clusters of galaxies seen to surround voids
in the universe; voids and string-like formations are seen and
predicted by many models of the cosmos. The newly discovered ring is
however at least ten times larger than known voids.
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.”
The team now want to find out more about the ring, and establish
whether the known processes for galaxy formation and large scale
structure could have led to its creation, or if astronomers need to
radically revise their theories of the evolution of the cosmos.
Media contact
Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7734 3307
Mob: +44 (0)794 124 8035
rm@ras.org.uk
Science contact
Prof Lajos Balazs
Konkoly Observatory
Budapest
Hungary
Tel: +36 1 3919354
lgbalazs@gmail.com
Further information
The new work appears in “A giant ring-like structure at 0.78 < z < 0.86 displayed by GRBs”,
Monthly Notices of the Royal Astronomical Society, L. G. Balazs, Z.
Bagoly, J. E. Hakkila I. Horvath, J. Kobori, I. R ́acz and L. V. T ́oth,
Oxford University Press.
Notes for editors
The Royal Astronomical Society (RAS), founded in 1820, encourages and
promotes the study of astronomy, solar-system science, geophysics and
closely related branches of science. The RAS organises scientific
meetings, publishes international research and review journals,
recognizes outstanding achievements by the award of medals and prizes,
maintains an extensive library, supports education through grants and
outreach activities and represents UK astronomy nationally and
internationally. Its more than 3800 members (Fellows), a third based
overseas, include scientific researchers in universities, observatories
and laboratories as well as historians of astronomy and others. Follow
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Source: Royal Astronomical Society (RAS)
