Cornell-Caltech Atacama telescope promises clues about formation of the Universe

http://www.news.cornell.edu/stories/...iovanelli.html


Cornell-Caltech Atacama telescope promises clues about formation of
the universe

By Lauren Gold )
May 1, 2006

The Atacama region of northern Chile is one of the highest and driest
places on Earth -- a contradictory landscape of parched ground, cool
salt lakes, archaeological treasures and the occasional startling
band of hot-pink flamingos.

In the coming years, astronomers say, it also will be the source of
some of the most meaningful and advanced research in astrophysics:
The site of a 25-meter class telescope sensitive enough to offer new
clues about the origin and early evolution of stars, interstellar
matter, planetary systems and, ultimately, about the formation of the
structure in the universe.

Riccardo Giovanelli, Cornell professor of astronomy, is leading the
effort to build the telescope, which will have unparalleled
sensitivity for detecting light in the submillimeter, or far
infrared, range of the electromagnetic spectrum. Radiation at
submillimeter wavelengths (longer than visible light but shorter than
radio waves) is normally difficult to detect from the ground because
it is easily absorbed by water vapor in the Earth's atmosphere. The
Atacama Desert's bone-dry climate and altitude of 5,000 meters
(16,500 feet) and higher, therefore, make it a unique and ideal spot
for ground-based far-infrared astronomy.

Under Giovanelli's guidance, and with private funding from retired
businessman Fred Young, Cornell Class of 1964, Cornell signed an
agreement with the California Institute of Technology (Caltech) in
2004 to collaborate on the project. Planners hope to begin
construction on the Cornell Caltech Atacama Telescope (CCAT) in 2007
and to see first light in 2012.

CCAT will take advantage of a rapidly advancing technological wave:
the development of so-called large format bolometer arrays (a
bolometer is an instrument for measuring radiant energy). Until a few
years ago, submillimeter telescopes formed images by observing one
pixel at a time, and currently operating arrays have a few hundred
pixels. CCAT will operate with tens of thousands and eventually
millions of pixels: a hugely increased capability that will allow
researchers to study in detail the formation of galaxies, stars and
planets, which are shrouded in clouds of gas and dust that block
radiation at optical wavelengths.

"In the submillimeter, you can actually pierce all the way through;
you can see the birth of cosmic structure taking place," said
Giovanelli.

The telescope will also be a powerful tool for studying objects in
the far regions of the solar system. "We don't know how many large
solar system bodies beyond Pluto and Charon are out there,"
Giovanelli said. "Current submillimeter telescopes can detect things
as big as Pluto, but nothing much smaller. This telescope will be
able to go to sizes all the way down to 50 to 100 kilometers, instead
of 1,000 kilometers."

On a much larger scale, CCAT will be capable of conducting
unprecedented surveys of extremely distant galaxies, allowing
scientists to witness their distribution at the epoch when galaxies
were forming. Scientists estimate that galaxies began to form about 1
billion years after the big bang, or between 12 and 13 billion years
ago. At that time the rate of star formation was much higher than it
is now, releasing a large amount of electromagnetic energy that was
emitted at short wavelengths, then subsequently absorbed by gas and
dust and re-emitted at much longer wavelengths. The expansion of the
universe then shifted that radiation to even longer wavelengths. As a
result, much of the light produced by just-forming galaxies reaches
us in the far infrared part of the spectrum.

As a survey tool, the Atacama telescope will be 30 times faster than
current facilities and much more sensitive, allowing scientists to
probe such fundamental questions as how galaxies form and how their
clustering properties evolved.

"The farther back in time you go, the less contrasted the pattern of
cosmic structure appears," said Giovanelli. "CCAT will tell us how
the large-scale structure tapestry of the cosmos changed its look,
from the moment when the first galaxies formed until now."

Another significant new telescope will share the desert with CCAT. A
$700 million project by the United States, Europe and other partners
to build a large array of millimeter antennae is under way and also
expected to be complete in 2012. The Atacama Large Millimeter Array
(ALMA), which will be operated as a public facility by the National
Radio Astronomy Observatory, will use interferometry to obtain
extremely high-resolution images of galactic and extragalactic
sources.

CCAT's chosen site will be 2,000 feet higher than ALMA's 16,500 feet;
but the two facilities, whose strengths complement each other, will
be close enough to allow convenient sharing of resources.

"ALMA will be good at making very detailed maps of very small areas,"
Giovanelli said. With CCAT, "we will be able to image very quickly
and with very high sensitivity very large areas. A CCAT image will
cover an area thousands of times bigger than an ALMA image. Objects
of special interest discovered by CCAT will be later imaged with ALMA
in order to detect finer structures. And access to CCAT will give us
a huge leverage arm in facilitating our access to ALMA."

A panel of experts appointed by the Cornell and Caltech
administrations and chaired by Nobel laureate Robert Wilson of
Harvard University agreed. "CCAT will revolutionize astronomy in the
far infrared/submillimeter band and enable significant progress in
unraveling the cosmic origin of stars, planets and galaxies," the
panel reported in February. "CCAT is very timely and cannot wait."

"CCAT will be a very beautiful tool for the study of galaxies at the
epoch of their formation," Giovanelli added. "It is going to be the
best instrument of its kind in the world. There is no question about
it."

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