(Proposal ID) S15A-044

(PI) Schulze, Andreas

(Proposal Title)
 An Imaging Survey for the Hobby-Eberly Telescope Dark Energy Experiment

(Abstract)
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will study the  
evolution of dark energy using the power-spectrum of ~ 1,000,000 Lyalpha  
emitting galaxies between 1.9 < z < 3.5. Beginning in mid 2015, a large suite 
of integral-field units will obtain R~800 spectra between 3500Angstrom and  
5500Angstrom over 300 deg^2 of sky (filling factor 1/4.5). Since whatever 
falls onto the  instrument's 34,000  1.''5 diameter fibers will be measured, 
this blind survey will generate a unique, unbiased spectral database of over 
3 x 10^6 objects that extends ~ 5 mag deeper than SDSS. Additional projects 
facilitated by these data include probing the history of star-formation as a 
function of environment, understanding Lyalpha emission in the context of 
galaxy evolution, examining the processes of cluster formation, and more. 
Complementary imaging is critical for HETDEX, since continuum detections 
(or limits) are  essential for excluding the foreground [O II] emitters which 
can contaminate the dark energy measurement. We propose to use Subaru's Hyper 
Suprime-Cam to image the primary HETDEX field to a 10 sigma depth of  g = 25.1.
 When combined with our spectroscopy, these data will enable us to measure  
the signature of baryonic acoustic oscillations at z ~ 2.4 and the evolution 
of dark energy.