YOUNGSTOWN — A Youngstown State University professor of astronomy has a significant role in creating the largest map of the cosmos ever.
John Feldmeier is the chief imaging scientist for the Hobby-Eberly Telescope Dark Energy Experiment, which recently began full scientific operations.
HETDEX is a large international consortium that involves about 100 scientists; Feldmeier has been part of the collaboration since 2011.
The experiment will create a three-dimensional map of 2.5 million galaxies to help astronomers understand how and why the expansion of the universe is speeding up over time.
Feldmeier earned a doctorate from Penn State University and joined the YSU faculty in 2006. He said he has been working on the project for 10 years.
“The project is a large project made up of hundreds of people,” Feldmeier said. “We (he and his students) only do a certain piece — but it’s very important.”
That piece is imaging the data found from other portions of the project. Feldmeier’s focus is to match up the other data to map the findings. Feldmeier likened the project to chocolate and peanut butter — both great alone but significantly better when combined.
“It’s combining (the parts) that make the data so amazing,” he said.
Three years into its quest to reveal the nature of dark energy, HETDEX is on track to complete the largest map of the cosmos ever. The team will create a three-dimensional map of 2.5 million galaxies that will help astronomers understand how and why the expansion of the universe is speeding up over time.
“HETDEX represents the coming together of many astronomers and institutions to conduct the first major study of how dark energy changes over time,” said Taft Armandroff, director of The University of Texas at Austin’s McDonald Observatory, in a news release.
The survey began in January 2017 on the 10-meter Hobby-Eberly Telescope at McDonald Observatory. Today, the survey is 38 percent complete.
“We’re over a third of the way through our program now, and we have this fantastic data set that we’re going to use to measure the dark-energy evolution,” astronomer Karl Gebhardt said.
“We’re getting to the point in the project where it’s getting very exciting,” Feldmeier said.
The survey works by aiming the telescope at two regions of the sky near the Big Dipper and Orion. For each pointing, the telescope records around 32,000 spectra, capturing the cosmic fingerprint of the light from every object within the telescope’s field of view.
“It’s actually a little mind-blowing, how much information is captured in this,” team member Gary Hill said.
These spectra are recorded via 32,000 optical fibers that feed into more than 100 instruments working together as one. This assembly is called VIRUS, the Visible Integral-field Replicable Unit Spectrograph. It’s a massive machine made up of dozens of copies of an instrument working together for efficiency. VIRUS was designed and built especially for HETDEX.
This makes VIRUS one of the most advanced astronomical instruments in the world.
To make the map needed for the dark-energy project, participants are combing through a billion spectra looking for examples of a specific type of galaxy. These galaxies range in distances from 10 billion to 11.7 billion light-years away, so they represent an epoch when the universe was only a few billion years old.
The HETDEX team expects to complete its observations by December 2023.
The project is led by The University of Texas at Austin McDonald Observatory and Department of Astronomy, with participation from Penn State University; Ludwig Maximilians University, Munich; the Max Planck Institute for Extraterrestrial Physics; the Institute for Astrophysics, Gottingen; the Leibniz Institute for Astrophysics, Potsdam; Texas A&M University; The University of Oxford; the Max Planck Institute for Astrophysics; The University of Tokyo; and the Missouri University of Science and Technology.
In addition to institutional support, HETDEX is funded by the National Science Foundation, the state of Texas, the U.S. Air Force and private individuals and foundations.
