 
Astronomers
detect distant quasar near outer limits of our universe
13
Apr 2000
By
Robert Sanders, Media Relations
BERKELEY
-- Astronomers taking advantage of the unparalleled light-collecting
power of the Keck Telescope in Hawaii have found the most distant
object in the universe, a quasar that must have been among the
first objects ever to form, according to an astronomer at the
University of California, Berkeley.
Quasars
are thought to be the early stages of galaxy formation, seen
today as bright but distant star-like objects. They are thought
to be fueled by a central black hole in a feeding frenzy, gobbling
up stars and emitting copious amounts of energy.
This
particular quasar, named SDSS 1044-0125, was identified as a
possibly distant quasar from data taken by the Sloan Digital
Sky Survey (SDSS) in March of this year, said survey spokesperson
Michael S. Turner of the University of Chicago and the U. S.
Department of Energy's Fermi National Accelerator Laboratory
(Fermilab).
Last
week a team of astronomers led by Marc Davis, the professor
of astronomy at the University of California, Berkeley, obtained
spectra of the object at the Keck II Telescope in Hawaii and
confirmed that it is a distant quasar.
With
a redshift of 5.8, the light we see was emitted about a billion
years after the birth of the universe, when it was 6.8 times
smaller than it is today, Davis said. A redshift of 5.8 means
the wavelength of light was shifted by 580 percent.
"It's
astounding," Davis said. "This is very close to the
limit we should be able to see in the universe."
Davis's
colleagues at the 10-meter Keck II telescope, which together
with Keck I are the largest optical and infrared telescopes
in the world, were Robert Becker of the UC Davis, Princeton
graduate student Xiaohui Fan and Dr. Richard L. White of the
Space Telescope Science Institute in Baltimore, Md.
Davis
said that quasars at this distance should be extremely rare,
and he is surprised that it was even detected. At about a million
to 10 million times the mass of our Sun, it is amazingly bright.
"Our
first question is, 'How does a thing like this get built and
form a black hole at the center in such a short time?'"
he said. "Based on our current understanding of how the
universe evolved, bright quasars like this shouldn't exist at
such a distance, or they should be very rare."
The
quasar is so distant that the expansion of the universe shifted
its light, originally emitted as ultraviolet, through the visible
into the infrared part of the spectrum.
"Anything
much farther away will be shifted so far into the infrared that
it will be beyond the ability of our instruments to detect,"
he said.
Twice
before, Sloan survey scientists have found quasars that have
broken the distance record. To date, the survey has discovered
thousands of quasars, including eight of the 10 most distant
known quasars and two-thirds of the quasars with redshifts greater
than 4.5.
According
to Richard Kron of the University of Chicago and Fermilab, the
SDSS quasar advantage comes from the size of the survey and
its unique ability to look at objects across five precisely
measured color bands. The survey digitizes images of 20,000
objects in every square degree of sky, and automated algorithms
select quasar candidates based on this color information. Distant
quasars take on the appearance of very red stars.
Scientists
hope to use quasars to chart the birth and formation of galaxies,
explore structure on the largest scales, and better understand
black holes. Already, said Princeton's Fan, he and others have
used the early Sloan sample to trace the time history of quasar
populations. Consistent with earlier studies, the SDSS data
show that the number of quasars rose dramatically from a billion
years after the Big Bang to a peak around 2.5 billion years
later, falling off sharply at lower redshift and, hence, later
times.
The
Sloan project will ultimately survey one quarter of the sky
and 200 million objects. A million or so of these will be quasars,
which numerous telescopes around the world will study further.
The
Sloan Digital Sky Survey is a joint project of The University
of Chicago, Fermilab, the Institute for Advanced Study, the
Japan Participation Group, The Johns Hopkins University, the
Max-Planck-Institute for Astronomy, Princeton University, the
United States Naval Observatory, and the University of Washington.
Funding for the project has been provided by the Alfred P. Sloan
Foundation, the SDSS member institutions, the National Aeronautics
and Space Administration, the National Science Foundation, the
U.S. Department of Energy, and Monbusho.
The
W. M. Keck Observatory, perched on the summit of Hawaii's dormant
Mauna Kea volcano, is operated by the California Institute of
Technology, the University of California and the National Aeronautics
and Space Administration. The telescopes, Keck I and II, were
made possible through grants totaling more than $140 million
from the W.M. Keck Foundation.
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