Cynthia L. Atwood, Science Correspondent
Yale University Office of Public Affairs
433 Temple St.
New Haven, CT 06520
(203) 432-1326, fax (203) 432-1323
[email protected]
CONTACT: Cynthia L. Atwood
For Immediate Release: Dec. 10, 1996
Yale University Leads Innovative International Collaboration
In Search of Dark Matter in the Universe
Powerful Schmidt Telescope Could Detect Black Holes, Dead Stars
New Haven, CT -- Yale University has entered a dark horse in the
international race to find dark matter, the 90 percent or more of the
universe's mass that is unseen and unknown but exerts a profound
influence on the distribution and shape of visible galaxies. Theories
about the composition of this missing matter range from exotic new
kinds of subatomic particles to black holes, burned out stars or
intergalactic dust and gas.
In an innovative international collaboration, astronomers and
physicists at Yale and Indiana universities, the University of the
Andes and the CIDA Observatory in Venezuela have pooled their
resources to equip a powerful telescope located high in the Andes
Mountains with a state-of-the-art detector system similar to that used
in particle physics.
Working on a limited budget, the Quest Project -- an acronym for
the Quasar Equatorial Survey Team -- will compete with a number of
multi-million-dollar dark matter projects now under construction. The
researchers hope to solve one of the most perplexing mysteries in
astrophysics.
"The Quest project has one of the largest detector systems
available today in astronomy, which will make the CIDA Schmidt
telescope one of the most powerful earth-based survey telescopes and
one that is ideally located near the equator," said Charles Baltay,
chairman of Yale's physics department. Yale scientists will install
the detector system later this winter and, in exchange, will receive
more than half of the telescope's precious observing time -- a huge
boon for the university's astronomers.
"I find it extremely satisfying that the same kind of detectors
designed to explore extremely small subatomic particles will be used
to survey vast stretches of the universe -- a difference in size of
approximately 40 orders of magnitude," he said. "It is impossible to
go from anything smaller to anything bigger."
The retrofitted telescope will systematically survey most of the
sky visible from the equator, a process that could take as little as
100 nights of clear observing, according to astronomer Sabatino Sofia,
who helped plan the CIDA Observatory in the 1970's before joining the
Yale faculty.
Professor Sofia, who is chairman of Yale's astronomy department,
also is helping to arrange an exchange of students and teachers among
the three participating universities. Altogether, 28 physicists,
astronomers and engineers are working on the Quest project, along with
about a dozen students, including four Yale undergraduates.
Using Light from Quasars to Probe the Universe
With the telescope in Venezuela, scientists can use the light from
quasars, which are the oldest and brightest objects in the universe,
to probe the universe for missing matter, said Professor Augustus
Oemler, former Yale astronomy department chairman and now director of
the Observatories of the Carnegie Institution of Washington. Quasars
are thought to represent an earlier, more active stage of galactic
evolution roughly 2.5 billion years after the "Big Bang" of creation,
which occurred about 15 billion years ago.
According to Einstein's General Theory of Relativity, the fabric
of spacetime is warped in the vicinity of massive objects like black
holes, causing light passing nearby to bend, Professor Oemler said.
The result is "gravitational lensing," a phenomenon first observed in
1979 and less than a dozen times since.
"When gravitational lensing occurs, light from a single source,
such as a quasar, appears as two or more images widely separated from
each other. These distinctive patterns of multiple images from a
single light source, called macrolensing, could tell us indirectly
about the presence of black holes or other invisible structures
scattered throughout the universe," Professor Baltay said.
Gravitational lensing also can cause an increase in the brightness
of light as it passes near a massive object, a phenomenon called
microlensing. The Yale project is expected to be unique in its
ability to detect both micro- and macro-lensing with its highly
sensitive CCD detectors.
Yale also is co-owner of the 3.5-meter WIYN telescope on Kitt
Peak near Tucson, Arizona, which astronomers can use for detailed
study of each of the hundreds of lensing events the scientists expect
to pinpoint with the Venezuela survey. Yale also will use its 1-meter
telescope in Chile and the 1-meter CIDA telescope in Venezuela to do
detailed follow-up work on the lensing events to determine the
expansion rate of the universe.
"When we look at quasars, we are looking far back in time at light
that has been traveling for billions of years. Therefore, we can
observe different stages of galactic evolution," said Professor
Baltay, who added that Quest scientists expect to survey about 600,000
quasars during the project. "We also can use quasars to measure vast
distances so we can estimate more accurately the rate at which the
universe is expanding, and thus calculate the age of the universe."
Is the Universe Smooth or Lumpy?
When the survey is completed, Quest astronomers will analyze the
masses of data to learn whether missing matter is distributed
relatively evenly throughout the universe or whether it is clumped
together, which could tell them whether the missing mass is primarily
in the form of subatomic particles or large objects such as black
holes or dark galaxies.
Identifying the missing matter could reveal whether the universe
will continue to expand or will eventually shrink back on itself like
a deflating balloon, ending in what has been dubbed the "Big Crunch."
Another possibility is that just enough missing matter exists to
eventually stop the universe's expansion but not to shrink it,
creating a stable universe, Professor Sofia said.
The search for dark matter also could help physicists understand
the highly energetic conditions that existed during the first moments
following the cataclysmic "Big Bang" that created the universe --
conditions they have attempted to recreate in gigantic nuclear
accelerators. "Astronomers need particle physicists in order to
understand the kinds of matter that dominate the universe.
Physicists, on the other hand, need astronomers because the universe
may, in the end, be the best laboratory available for studying
subatomic particles at their highest energies," Professor Baltay
said in explaining the motivation behind the Quest collaboration.
Yale's CCD (silicon charged coupled device) detector system, which
is based on the same technology as an everyday video camcorder, will
produce extremely clear images to a resolution of 15 microns, which is
less than 1/1,000th of an inch, said Professor Baltay. He has been
working for more than a decade on this technology as part of a
$60-million, long-term collaboration with the Stanford Linear
Accelerator Center, the Massachusetts Institute of Technology and
Rutherford Laboratories in England.
Adapting the detector for the CIDA Schmidt Telescope took two years.
His upgraded design features 96 CCD silicon chips with a total
capacity of 400 million pixels, which will enable the detector system
to gather an extraordinary 167 billion pixels of data each night.
###
Note to Editors: Charles Baltay, (203) 432-3386, is active not only
in astrophysics but also does research in elementary particle physics,
where he is involved in a large project at the Stanford Linear
Accelerator Center to carry out precision tests of the electro-weak
interactions at very high energies.
Augustus Oemler, (818) 304-0260, participated in discovering a void
in the universe large enough to swallow 2,000 galaxies the size of the
Milky Way. He also is known for exploring the internal properties of
galaxies and for theorizing the Butcher-Oemler Effect, which refers to
the relatively rapid evolution of galaxies during the latest third of
the universe's history.
Sabatino Sofia, (203) 432-3011, is associate director of Yale's Center
for Solar and Space Research. He developed the Solar Disk Sextant,
which is a candidate for installation in the year 2002 aboard the U.S.
space station. The experiment is designed to provide more accurate
measurements of changes in the sun's diameter and shape, and its
long-term cyclic changes in energy output.
Collaborators on the Quest project are:
Ä At Yale: Professors William van Altena, Charles Bailyn, Charles
Baltay, Paolo Coppi, Gus Oemler, Brad Schaefer and Sabatino Sofia;
engineers William Emmet and John Sinnott; researcher Jeffrey Snyder;
graduate students Peter Andrews, Volker Bromm and Chris Sabbey; and
undergraduate students Ben Mazin, Scott Rickert, Neelima Sehgal and
Trevor Uhl.
Ä At Indiana University, Bloomington: Professors Kent Honeycutt,
Stuart Muffson, Jim Musser and Richard Heinz; engineers Bryce Adams
and Mark Gebhard; and graduate student Mike Barnett.
Ä At CIDA Observatory: Researchers Jurgen Stock, Gustavo Bruzual,
Gladis Magris, and Carlos Abad; engineers Gerardo and Gustavo Sanchez,
Franco Della Prugna and Hans Schenner; students Cesar Biceno and Anna
Katherina Vivas.
Ä At University of the Andes: Researchers Ignacio Ferrin, Francisco
Fuenmayor and Patricia Rosenzweig; and student Julian Suarez.
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