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Events on Wednesday, October 13th, 2010

Special Wednesday Astronomy Talk
The Hobby-Eberly Telescope Dark Energy Experiment
Time: 12:00 pm
Place: 4421 Sterling Hall
Speaker: Gary Hill, University of Texas
Abstract: The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) aims to make a direct detection of dark energy at z~3, in the case that it is a cosmological constant. HETDEX uses baryonic acoustic oscillations and the shape of the Lyman-alpha emitting (LAE) galaxy power spectrum to constrain H(z) and Da(z) to percent levels. As a result, the experiment will place tight constraints on possible dark energy evolution, complementing studies of the phenomenon at low redshift. HETDEX will also provide the most accurate constraint on the curvature of the Universe.<br>
HETDEX will outfit the 10 m HET with a new wide field and an array of at least 150 integral-field spectrographs to survey a 400 sq. degree area in the north galactic cap. Each fiber-coupled unit spectrograph will cover 350-550 nm, simultaneously at 6 A resolution, providing ~36,000 spectra per exposure. This instrument, called VIRUS, will open up surveys of the emission-line universe for the first time, and in particular will be used to detect ~0.8 million LAE galaxies with 1.9 &lt; z &lt; 3.5 and more than a million [OII] emitting galaxies with z &lt; 0.5. The 3-D map of LAE galaxies in 9 cubic Gpc volume will be used to constrain the expansion history at this early epoch.<br>
The prototype of the VIRUS unit spectrograph (VIRUS-P) is a powerful instrument in its own right. Used on the McDonald 2.7 m Smith reflector, it covers the largest area of any integral field spectrograph, and has coverage down to 340 nm. It is currently in use for a pilot survey to better measure the properties of LAE galaxies in support of HETDEX, among other investigations where it is uniquely powerful.<br>
I will describe the motivations for HETDEX and preliminary results from the Pilot Survey and look forward to completion of VIRUS on the upgraded HET as a unique facility in Astronomy <br>
Host: Marsha Wolf
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