Was Einstein's 'biggest blunder' a stellar success? (Forwarded)

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University of Toronto
Toronto, Canada

Contact:

Professor Ray Carlberg
Department of Astronomy and Astrophysics
416-978-2198

Nicolle Wahl
U of T Public Affairs
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Nov 22/05

Was Einstein's 'biggest blunder' a stellar success?

New supernovae study offers tantalyzing clues about dark energy

The genius of Albert Einstein, who added a "cosmological constant" to
his equation for the expansion of the universe but later retracted it,
may be vindicated by new research.

The enigmatic dark energy that drives the accelerating expansion of the
universe behaves just like Einstein's famed cosmological constant,
according to the Supernova Legacy Survey (SNLS), an international team
of researchers in France and Canada that collaborated with large
telescope observers at Oxford, Caltech and Berkeley. Their observations
reveal that the dark energy behaves like Einstein's cosmological
constant to a precision of 10 per cent.

"The significance is huge," said Professor Ray Carlberg of the
Department of Astronomy and Astrophysics at U of T. "Our observation is
at odds with a number of theoretical ideas about the nature of dark
energy that predict that it should change as the universe expands, and
as far as we can see, it doesn't." The results will be published in an
upcoming issue of the journal Astronomy & Astrophysics.

"The Supernova Legacy Survey is arguably the world leader in our quest
to understand the nature of dark energy," said study co-author Chris
Pritchet, a professor of physics and astronomy at the University of
Victoria in British Columbia, Canada.

The researchers made their discovery using an innovative, 340-million
pixel camera called MegaCam, built by the Canada-France-Hawaii Telescope
and the French atomic energy agency, Commissariat à l'Énergie Atomique.
"Because of its wide field of view -- you can fit four moons in an image
-- it allows us to measure simultaneously, and very precisely, several
supernovae, which are rare events," said Pierre Astier, one of the
scientists with the Centre National de la Recherche Scientifique (CNRS)
in France.

"Improved observations of distant supernovae are the most immediate way
in which we can learn more about the mysterious dark energy," adds
Richard Ellis, a professor of astronomy at the California Institute of
Technology. "This study is a very big step forward in quantity and quality."

Study co-author Saul Perlmutter, a physics professor at the University
of California, Berkeley, says the findings kick off a dramatic new
generation of cosmology work using supernovae. "The data is more
beautiful than we could have imagined 10 years ago -- a real tribute to
the instrument builders, the analysis teams and the large scientific
vision of the Canadian and French science communities."

The SNLS is a collaborative international effort that uses images from
the Canada-France-Hawaii Telescope, a 3.6-metre telescope atop Mauna
Kea, a dormant Hawaiian volcano. The current results are based on about
20 nights of data, the first of over nearly 200 nights of observing time
for this project. The researchers identify the few dozen bright pixels
in the 340 million captured by MegaCam to find distant supernovae, then
acquire their spectra using some of the largest telescopes on earth --
the Frederick C. Gillett Gemini North Telescope on Mauna Kea, the Gemini
South Telescope on the Cerro Pachón mountain in the Chilean Andes, the
European Southern Observatory Very Large Telescopes (VLT) at the Paranal
Observatory in Atacama, Chile, and the Keck telescopes on Mauna Kea. The
SNLS is one component of a massive 500-night program of imaging being
undertaken as the CFHT Legacy Survey.

"Only the world's largest optical telescopes -- those from eight to 10
metres in diameter -- are capable of studying distant supernovae in
detail by examining the spectrum," said Isobel Hook, an astronomer in
the Department of Astrophysics at Oxford University.

The current paper is based on about one-tenth of the imaging data that
will be obtained by the end of the survey. Future results are expected
to double or even triple the precision of these findings and
conclusively solve several remaining mysteries about the nature of dark
energy.

The research was funded by the Canada-France-Hawaii Telescope, the
Commissariat à l'Énergie Atomique (CEA), Centre National de la Recherche
Scientifique, Institut National des Sciences de l'Univers du CNRS, the
Natural Sciences and Engineering Research Council of Canada, the
National Research Council of Canada's Herzberg Institute of
Astrophysics, the Gemini Observatory, the Particle Physics and Astronomy
Research Council, the W. M. Keck Observatory and the European Southern
Observatory.

IMAGE CAPTION:
[http://cfht.hawaii.edu/News/SNLS_Nov2005/SNLS_fig.gif (213KB)]
This supernova is as bright as 100 billion Sun-like stars. It exploded 3
billion years ago. At the maximum of its brightness, it was 25 000 times
less bright than the blue star seen in the middle of the image. This
central blue star is 100 times less bright than the faintest star
visible with the naked eye.

Copyright CFHTLS/SNLS/Terapix