Using a powerful instrument on a telescope in Hawaii, UK astronomers have
found ashes from a generation of stars that died over 10 billion years ago.
This is the first time that the tell-tale cosmic dust has been detected at
such an early stage in the evolution of the universe.
Dr. Kate Isaak of Cambridge University will be announcing these exciting new
results at the National Astronomy Meeting in Bristol on 11th April 2002.
Using the SCUBA (Submillimetre Common-User Bolometer Array) camera on the
James Clerk Maxwell Telescope in Hawaii, the team of British astronomers
observed a sample of the most distant quasars known, to detect their primeval
‘host’ galaxies. The submillimetre wavelength radiation detected by SCUBA
comes from large amounts of cool dust, a substance formed in
supernovae and/or the atmospheres of old stars.
Team leader Dr. Robert Priddey (Imperial College) said “These quasars are the
most distant submillimetre sources known. We’re looking more than nine-tenths
of the way back to the birth of the universe in the Big Bang.”
The quasars are extremely far from us, as measured by their very high
redshifts of 5-6. These huge distances mean that their light was emitted when
the universe was less than a tenth of its current age — a mere billion years
after the Big Bang. Consequently, the host galaxies are
caught when they are extremely young, and when astronomers might expect to
see a burst of star formation.
Dr. Priddey explained, “It’s amazing enough that these quasars, powered by
billion solar mass black holes, should already exist only a billion years
after the Big Bang. That these quasars also appear to contain so much dust
yields important clues to the formation of massive galaxies in the youthful
cosmos.”
Although it is not yet known whether the dust in these quasars is heated by
hot, young stars within the galaxy, or directly by the quasar itself, the
very existence of the dust and its constituent elements such as silicon and
carbon implies that a large mass of stars have already been born, grown old
and expired, within only a billion years of the Big Bang.
Dr. Isaak said, “These observations of very distant quasars are part of a
programme looking at the submillimetre emission of quasars from low to high
redshift. If we hunt for ever higher redshift quasars, we might catch the
epoch at which the first dust forms.”
Team member Dr. Richard McMahon (University of Cambridge) added “The stars
that made the carbon and silicon in these quasars are probably like the stars
that made the carbon in our own bodies. It is very exciting to be able to
learn when the chemical elements in our bodies were made. These quasars seem
to be forming stars at a rate of around 1000 stars like the
Sun per year.”
NOTES FOR EDITORS:
AN IMAGE OF THE JAMES CLERK MAXWELL TELESCOPE IN HAWAII IS AVAILABLE AT:
http://www.jach.hawaii.edu/~douglas/quasars/
Quasars are incredibly bright and distant objects, thought to be examples of
Active Galaxies, which shine hundreds of times brighter than normal galaxies
like our own. They are powered by gas in the galactic core falling into a
‘supermassive’ black hole which can be as much as one
billion times as massive as our own Sun. For a brief period, the compact
nucleus shine brighter than all the stars in the galaxy.
SCUBA (the Submillimetre Common-User Bolometer Array) is currently the
world’s most powerful “submillimetre-wave” camera. It has revolutionised our
knowledge of many areas of astronomy. The instrument contains highly
sensitive detectors called bolometers, which are cooled to 0.06 degrees above
absolute zero (-273 degrees Centigrade) to make them super-sensitive to the
incoming submillimetre waves. It has been in operation on the James
Clerk Maxwell Telescope (JCMT) in Hawaii for about five years.
The host galaxies detected by SCUBA contain dust with a mass about 100
million times that of our Sun. The black holes in their cores are at least
one billion times as massive as our Sun, and are swallowing about 10-100
solar masses of material per year.
‘Redshift’ measures the factor by which the light we observe from distant
sources has been stretched, as the Universe expands during the course of its
journey. The higher the redshift, the further away the source. The most
distant of the quasars has a redshift of six, meaning that it emitted the
light we detect when the radius of the Universe was one seventh of its
current value. At this time, the universe was about a billion years old,
compared to its current age of over 10 billion years.
Contact details:
Dr. Robert Priddey Astrophysics Group Blackett Laboratory Imperial College London SW7 2BW UK Email: r.priddey@ic.ac.uk Tel: +44 (0)20 7594 7543 Fax: +44 (0)20 7594 7541 Dr. Kate Isaak Astrophysics Group Cavendish Laboratory Madingley Road Cambridge CB3 0HE UK Email: isaak@mrao.cam.ac.uk Tel: +44 (0)1223 339242 Fax: +44 (0)1223 354599 Dr. Richard McMahon Institute of Astronomy University of Cambridge Madingley Road Cambridge CB3 OHA UK Email: rgm@ast.cam.ac.uk Tel: +44 (0)1223 337548/19 Mobile: 07885 409019 Fax: +44 (0)1223 337523 Douglas Pierce-Price Joint Astronomy Centre 660 North A`ohoku Place Hilo Hawaii 96720 USA Email: d.pierce-price@jach.hawaii.edu Website: http://www.jach.hawaii.edu Tel: +44 (0)117 954 5913 (until 12th April 2002) +1 808 969 6524 (after 12th April 2002) Fax: +1 808 961 6516 (after 12th April 2002)
