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The structure of our Universe has been mapped out to a distance of 14
billion light-years — almost as far as we can see — by astronomers
who have observed 11,000 quasars with the Anglo-Australian Telescope in
eastern Australia, in the largest quasar redshift survey to date. The
structure is much lumpier at large scales than anyone predicted. The
findings will be presented simultaneously on Wednesday 4 April by Dr.
Robert Smith of Liverpool John Moores University at the UK National
Astronomy Meeting in Cambridge, UK, and by Professor Tom Shanks of the
University of Durham at ‘The Dark Universe’ symposium at the Space
Telescope Science Institute, Baltimore, USA.
“The lumpiness we see at very large-scales must be almost entirely
determined by the conditions in the fireball of the Big Bang during the
first second of the Universe’s life,” said Professor Shanks, co-leader
of the two-degree field (2dF) quasar survey.
“For this reason, we can say that the survey quasars are truly tracing
the map of creation.”
Cosmological models that predict less lumpiness at large scales are in
trouble, said Dr. Smith.
“These include some of the standard cosmological models with lots of
‘dark matter’ built in,” he said.
Quasars are the bright cores of distant galaxies. They make exceptionally
luminous ‘cosmic beacons’ that can be easily seen out to a distance of
10 billion light-years, much further than galaxies.
The unprecedented size of the 2dF survey means it can capture structure
on scales of up to 1000 million light-years, which has never been
possible before.
“Imagine the Universe is a room. Previous surveys have involved peering
through the keyhole to try to make out the pattern of the wallpaper,”
said Professor Brian Boyle, survey co-leader and Director of the
Anglo-Australian Observatory. “Now we’ve opened the door at least a
chink.”
Averaged over the whole volume of the survey, the quasars are clustered
to the same extent as local, optically selected galaxies — a result
previously only hinted at.
Because light takes a long time to travel vast distances, the most
distant quasars we can see existed early in the history of the
Universe — 14 billion years ago.
“As far back as we look in this survey, we see the same strength of
quasar clustering,” said 2dF team member Dr Scott Croom of the
Anglo-Australian Observatory.
“Imagine that the quasars are streetlights, marking out the structure
of a city such as New York. It’s as if we visited the city when it was
still a Dutch colony, yet found the same road pattern that exists today.”
The first instalment of data from the two-degree (2dF) quasar survey
will be released to the world-wide astronomical community this week.
Now 60% complete, the survey has already netted more quasars than were
previously known. When finished in 2002 it will have measured the
redshifts of 25,000 quasars — fifty times more than the largest
previous survey.
The completed survey will allow many new cosmological studies, including
measurements of the Universal space curvature by foreground galaxies
‘gravitationally lensing’ the light from background quasars.
Research findings from the 2dF quasar survey are being published as a
series of papers in the Monthly Notices of the Royal Astronomical
Society. The papers on quasar clustering are, “The 2dF QSO Redshift
Survey – II. Structure and evolution at high redshift” (posted at
http://xxx.lanl.gov/abs/astro-ph/0012375) and “The 2dF QSO Redshift
Survey – IV. The QSO Power Spectrum from the 10K Catalogue”
(http://xxx.lanl.gov/abs/astro-ph/0102163).
The members of the 2dF quasar survey team are: Professor Brian Boyle,
Anglo-Australian Observatory; Professor Tom Shanks, University of
Durham; Dr Lance Miller, University of Oxford; Dr Scott Croom,
Anglo-Australian Observatory; Ms Nicola Loaring, University of Oxford;
Dr Robert Smith, Liverpool John Moores University; Dr. Fiona Hoyle,
Drexel University; and Dr. Phil Outram, University of Durham.
IMAGES
Images available at http://www.aao.gov.au/press/cosmicbeaconimages.html
Anglo-Australian Observatory
Epping, NSW, Australia
CONTACTS
Dr Scott Croom, Anglo-Australian Observatory (Sydney)
scroom@aaoepp.aao.gov.au
+61-2-9372-4846 (work)
+61-2- 9878-5626 (home)
Professor Brian Boyle, Anglo-Australian Observatory
director@aaoepp.aao.gov.au
2-6 April, contactable via the Press Room at the National Astronomy
Meeting:
+44 (0)1223-313724
+44 (0)1223-313754
+44 (0)1223-315553
Professor Tom Shanks, University of Durham
tom.shanks@durham.ac.uk
To 30 March, +44-191-3742-171
31 March-6 April +1- 410-235-8600 evenings only
2-6 April +1-410-338-4707 daytime
Dr Robert Smith, Liverpool John Moores University
rjs@staru11.livjm.ac.uk
2-6 April, contactable via the Press Room at the National Astronomy
Meeting:
+44 (0)1223-313724
+44 (0)1223-313754
+44 (0)1223-315553
