Hobby-Eberly Telescope Dark Energy Experiment ( HETDEX )

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" Astronomers Create the Largest 3D Map of the Early Universe’s Hydrogen Glow " - Gadgets360

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is a major spectroscopic survey at McDonald Observatory aimed at understanding dark energy—the force accelerating the universe's expansion. Using the 10-meter Hobby-Eberly Telescope (HET) and VIRUS spectrographs, it maps over one million galaxies 9–11 billion light-years away. 

HETDEX is currently collecting data on at least one million galaxies that are 9 billion to 11 billion light-years away, yielding the largest map of the early universe ever produced. 

Key Details of HETDEX:

  1. Goal: To measure the expansion rate of the universe and determine if dark energy changes over time by mapping the 3D positions of over a million distant galaxies (specifically, Lyman-alpha emitters).
  2. Instrument: The survey uses VIRUS (Visible Integral-Field Replicable Unit Spectrograph), which consists of 150 spectrographs connected by 33,000+ optical fibers to the telescope.
  3. Method: It conducts an untargeted spectroscopic survey over a 540  area, allowing it to detect not just galaxies, but also active galactic nuclei (AGN).
  4. Collaboration: Led by The University of Texas at Austin McDonald Observatory and Penn State, with international partners including institutes in Germany and Japan.
  5. Citizen Science: The "Dark Energy Explorers" project on Zooniverse allows volunteers to help classify galaxies, reducing manual workload by 90%.
  6. Timeline: The survey began full operation around 2020, aiming to map galaxies from 9 to 11 billion years ago to test the cosmological constant. 

HETDEX is crucial for understanding the expansion history of the universe and provides data that complements other missions like Euclid. 

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