HETDEX: The HET Dark Energy Experiment

Astronomy is competitive. To attack the big questions, we need to keep investing in forefront facilities. The University of Texas McDonald Observatory can achieve this in a very cost-effective way by upgrading the Hobby-Eberly Telescope (HET) and adding to it innovative new instrumentation. At the same time this upgrade will allow Texas astronomers to answer the biggest question in all of science.

Dark Energy and Dark Matter

We only understand 4% of what makes up the universe. The nature of dark matter and dark energy is the greatest and most exciting problem in all of science. Dark energy is the name given to the phenomenon of the accelerating universe, whose expansion is speeding up over time.

Science does not know what dark energy is. Is it new particles? Energy of the vacuum of space? A change in the law of gravity? We know how to find out. Texas astronomers can differentiate between these possibilities with new facilities. Explaining dark energy will cause a fundamental change in our understanding of the laws of nature.

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)

• HETDEX is the quickest and most cost-effective project to uncover the secrets of dark energy. It uses our large Hobby-Eberly Telescope and an innovative new instrument called VIRUS to survey the sky ten times faster than existing facilities worldwide.

• HETDEX is competitive with projects costing billions that are being proposed worldwide. Only three projects including HETDEX are currently moving forward. Of these, HETDEX is in the lead at a cost of $34 million — lowest cost of all proposed projects.

• HETDEX will make the largest map of the Universe ever, traced by a million galaxies.

• HETDEX looks back in time 10 billion years.

• HETDEX will measure how dark energy changes with time: It is better than other experiments at measuring the change because it looks back so far in time; a change in the properties of dark energy will be the key discriminator between the different possibilities for the nature of dark energy.

HET Upgrade and VIRUS

HETDEX will upgrade the Hobby-Eberly Telescope to look at 25 times more sky, increasing our field of view to half the area of the Moon. This will be accomplished by adding new optics and an innovative new instrument to the HET, known as VIRUS. The VIRUS instrument will consist of 150 copies of a simple spectograph, replicated cheaply. We are pioneering this approach to save on cost and to remove engineering risk by prototyping the unit.

How HETDEX Works

Together, the upgraded HET and VIRUS will execute the largest astronomical survey ever made. This facility will be unmatched in the world, giving Texas astronomers the ability to survey the sky 10 times faster than any existing facility worldwide. It has the power to address the problem of dark energy. In short, the HET makes HETDEX work.

HETDEX Fast Facts and Benefits

• It will answer a fundamental question about our Universe and generate great public interest.

• Led by UT Austin with strong participation from Texas A&M and a small number of other institutions in the US and Germany.

• The project and fantastic facility that will result will attract the best researchers and students to Texas, which in turn seeds the next generation of scientists and engineers.

• The project Web site — HETDEX.org — has already proven to be a great resource and investment.

• HETDEX will be a catalyst for attracting the next generation into science.

• There is great need to attract and retain K-12 students in science, and the McDonald Observatory Education and Outreach Office has the means to bring this exciting story to teachers and students and use it as a tool to generate excitement that will follow through to the workforce.

• We are at a revolutionary time in science and Texas can play a pivotal role that will be reported in K-12 and university textbooks for decades.

HETDEX Partners

• The University of Texas at Austin McDonald Observatory
• Texas A&M University
• Max-Planck-Institut fuer Extraterrestrische Physik
• Pennsylvania State University
• Ludwig-Maximilians-Universität Munchen
• Astrophysical Institute Potsdam

For more details on this project, visit http://hetdex.org.