New Instrument, Telescope Upgrades Enable Pioneering Dark EnergyExperiment at McDonald Observatory (Forwarded)

McDonald Observatory
University of Texas
Fort Davis, Texas

Contact:
Rebecca Johnson, 512-475-6763

Science Contacts:
Dr. Karl Gebhardt, 512-471-1473
Dr. Gary Hill, 512-471-1477

10 January 2008

New Instrument, Telescope Upgrades Enable Pioneering Dark Energy
Experiment at McDonald Observatory

AUSTIN, Texas -- An experiment to determine the nature of "dark energy,"
that mysterious force that's causing the universe's expansion to speed up,
is driving telescope upgrades and the creation of new instruments at
McDonald Observatory in West Texas. The exciting science results already
obtained from this project demonstrate the power of the researchers'
approach.

University of Texas at Austin astronomers Karl Gebhardt and Gary Hill will
detail the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) at a
news conference at the 211th meeting of the American Astronomical Society
today.

Planned upgrades to the Hobby-Eberly Telescope (HET), one of the largest
telescopes in the world, include a new top end to widen the telescope's
field of view, and a new instrument. Called VIRUS (Visible Integral-field
Replicable Unit Spectrograph), it will be placed at the telescope's prime
focus.

"This is the Henry Ford approach to doing astronomy," Hill said, citing
the assembly-line nature of building the 145 copies of a simple
spectrograph that will make up VIRUS. "It's a new mode for building big
instruments."Once in place, VIRUS will map the positions of more than a
million galaxies in three dimensions over 100 nights. Scientists will then
study this map for evidence of "baryonic acoustic oscillations," a pattern
of sound waves imprinted on the universe at a very early time after the
Big Bang.

By looking at galaxies at different distances, the survey will map the
changes in the pattern of baryonic acoustic oscillations over time,
effectively providing us with evidence of how dark energy has changed over
the history of the universe.

This approach to studying dark energy employs very simple physics, the
team says. Further, because the HETDEX project is designed in phases, it
will accommodate changes in scientific understanding along the way. That's
important, the team said, as "our ignorance is so great."

The mystery of dark energy has been called the greatest problem in all of
science today. There are more than a dozen projects preparing to study
dark energy, some costing more than $1 billion and planned by federal
agencies like NASA, the Department of Energy, and the National Science
Foundation, as well as several international institutions.

HETDEX is a small but powerful project based at McDonald Observatory with
the cooperation of the HET partner institutions, as well as Germany's
Astrophysikalischen Institut Potsdam. Texas A&M University and Texas Tech
University are also involved in the project.

Costing $34 million, two-thirds of which already has been raised, HETDEX
is relatively inexpensive when compared to the cost projections for large
federal dark energy projects. A small project, HETDEX can move quickly and
will have results in the near-term (2010-2013).

The HETDEX team has built a prototype of the VIRUS instrument, consisting
of a single spectrograph, and deployed it on the 2.7-meter Harlan J. Smith
Telescope at McDonald Observatory to carry out a pilot survey for the
HETDEX project. This end-to-end test "mitigates our risk quite
extensively," Gebhardt said.

Not only that, but it's enabling some other exciting science, too,
Gebhardt said. Many of the projects now under way with the VIRUS prototype
are being presented at the American Astronomical Society meeting. They
show the instrument's versatility, ranging from topics of dark matter in
cluster galaxies (poster 011.22 by Jeremy Murphy), to studies of the
extended halo of a radio galaxy (poster 044.02 by Joshua Adams), to
studies of a planetary nebula (poster 100.04 by Sehyun Whang).

The VIRUS prototype is a great instrument in its own right, but "when you
multiply that by 145 and put it on a 10-meter telescope," Gebhardt said,
referring to HET, "it's just tremendous what we're going to be able to
do."

The Hobby-Eberly Telescope is a joint project of the University of Texas
at Austin, the Pennsylvania State University, Stanford University,
Ludwig-Maximillians-Universität München, and Georg-August-Universität
Goettingen.

[NOTE: Images supporting this release are available at
http://mcdonaldobservatory.org/news/...2008/0110.html ]