Dark Energy Explorers

What is the Hobby-Eberly Dark Energy Experiment (HETDEX)?

During five years of observations, the Hobby-Eberly Dark Energy Experiment (HETDEX) will find over one million galaxies that are 9 billion to 11 billion light-years away, yielding the largest map of the universe ever produced. The map will allow HETDEX astronomers to measure how fast the universe was expanding at different times in its history. Changes in the expansion rate will reveal the role of dark energy at different epochs. Various explanations for dark energy 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.

[Credit:NASA/WMAP Science Team]

How will HETDEX understand Dark Energy?

HETDEX will produce its map by using a set of small-unit spectrographs mounted on the Hobby-Eberly Telescope (HET), a 10 meter telescope located at the McDonald Observatory in West Texas. Known as VIRUS — Visible Integral-Field Replicable Unit Spectrographs, each unit is identical to all the others and connected to HET.

A spectrograph collects spectral lines. A spectral line is a line in a spectrum, resulting from emission or absorption of light in small wavelength ranges. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected "fingerprints" of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets. A shift in the positions of the spectral line(s) in our data tells us the distance to the galaxy so we can create a 3D map of the night sky. An in-depth explanation of the VIRUS instrumentation can be found here: https://instrumentation.tamu.edu/instruments/hetdex/

For almost every "dark" night (when the moon is not visible and the sky is clear) since 2016, HETDEX has assisted us in detecting data from our universe. The HETDEX team then cleans, collects and catalogs the data on a nightly basis. Each night, thousands of potential distant galaxies are discovered, allowing for volunteers like you to help us classify them.

How will we use your classifications?

The most difficult task is determining which galaxies come from our epoch of interest (10-11 billion years ago at z~2-3) and which ones are nearby. We need your help to identify the signals that are from distant galaxies. These galaxies, known as Lyman Alpha Emitters (LAEs), are known for brightly emitting at one distinct wavelength region. They show up as relatively faint blips or dots on a CCD image. They aren't as pretty as nearby galaxies, but these blips contain information about a galaxy's position, distance and brightness which will help HETDEX map out the clustering of galaxies and figure out how dark energy influenced the growth of matter in the early universe.

We also need your help to identify false or bad detections from our telescope. By doing this you will be helping identify the real galaxies from the fake ones which will allow us to conduct the dark energy science. We can then use those classifications as a pure training set for machine learning! Head on over to the Results page to learn more about how we are using these results!

Want to know more? Check out our Dark Energy Explorers YouTube Channel

We hold fun live events like a tour of the Hobby-Eberly Telescope, the third largest telescope in the world!

We are an official NASA partner and you can check out science.nasa.gov/citizenscience for more NASA Participant Science Projects!