HETDEX is a major experiment to search for dark energy. It uses one of the currently largest optical telescopes - the Hobby-Eberly Telescope at McDonald Observatory - and 156 separate spectrographs to map the three-dimensional positions of one million galaxies.
During five years of observations, HETDEX will collect data from galaxies whose light has travelled for 11 billion years before reaching us, yielding a detailed map of their locations. This map will allow HETDEX astronomers to measure how fast the universe was expanding at different times in its history. Changes in the expansion rate can test what role dark energy may have played at different epochs. Various explanations for dark energy and its alternatives predict different changes in the expansion rate, so by providing exact measurements of the expansion, the HETDEX map will eliminate some of the competing ideas.
Instrument and observing program for ground-based telescope
Member of the collaboration
Data-gathering operations have begun, with the survey completion expected in 2023
Optical and Interpretative Astronomy (web pages of the MPE department involved in the project)